diff --git a/README.md b/README.md
index 2ee60cc..8eef17e 100644
--- a/README.md
+++ b/README.md
@@ -1188,11 +1188,12 @@ The wallet takes the `decimals` from these sources, in this order
   "Use Blockscout" is on (`tokenSourcesByChainId()` in
   `src/popup/views/helpers.js`).
 
-The token's name comes from the same sources. While "Use Blockscout" is off, a
-token gets a line under it when the bundled list and the tracked tokens lack its
-name or decimals. The line says "Blockscout's report of your balances is not
-used to name this token, because "Use Blockscout" is off in Settings." These
-screens show the line:
+The token's name comes from the same sources. The bundled token list is used
+only for a token on Ethereum Mainnet. While "Use Blockscout" is off, a token
+gets a line under it when the bundled list and the tracked tokens lack its name
+or decimals. The line says "Blockscout's report of your balances is not used to
+name this token, because "Use Blockscout" is off in Settings." These screens
+show the line:
 
 - TxApproval and SignApproval
 - WaitTx, SuccessTx and ErrorTx, which follow TxApproval
@@ -1473,20 +1474,20 @@ tracked.
 
 A tracked token is shown when its balance is nonzero, and any other ERC-20 when
 its balance is nonzero and it is in the bundled known-token list or has 1,000 or
-more holders. A token claiming a symbol from the bundled list from any other
-contract address is always dropped, tracked or not, and so is any token claiming
-a symbol that belongs to the native asset and therefore has no legitimate
-contract at all (`"ETH"`, and every network's `nativeCurrency`, such as
-`"SepoliaETH"`, on every network). That filter is unconditional — the "Hide
-tokens with fewer than 1,000 holders" setting governs the transaction history
-and the send-screen token selector, not this list. A token's holder count is
-unknown when the explorer reports none, or reports anything other than a whole
-number written in digits alone, such as `1,000` or `1e3` (`parseHoldersCount()`
-in `src/shared/holders.js`). This list does not take an unknown count as 1,000
-or more, so such a token is shown only when it is on the bundled list or
-tracked. Every nonzero holding of a token shown is stored exactly, however
-small, but a holding below 0.000001 is left out of the balance lists, the
-send-screen token selector, the address total and the remove-address warning
+more holders. On Ethereum Mainnet, a token that claims a bundled token's symbol
+from another contract is always dropped, tracked or not. On every network, a
+token claiming a label of the native asset is always dropped. Those labels are
+`"ETH"` and each network's `nativeCurrency`, such as `"SepoliaETH"`. The balance
+list applies all three rules whatever the settings say. The "Hide tokens with
+fewer than 1,000 holders" setting governs only the transaction history and the
+send-screen token selector. A token's holder count is unknown when the explorer
+reports none, or reports anything other than a whole number written in digits
+alone, such as `1,000` or `1e3` (`parseHoldersCount()` in
+`src/shared/holders.js`). This list does not take an unknown count as 1,000 or
+more, so such a token is shown only when it is on the bundled list or tracked.
+Every nonzero holding of a token shown is stored exactly, however small, but a
+holding below 0.000001 is left out of the balance lists, the send-screen token
+selector, the address total and the remove-address warning
 (`isBelowOneMillionth()` in `src/shared/amountDisplay.js`). The Send and
 confirmation screens show it when its token is the one being sent. Tracked
 tokens with a zero balance are listed as well while "Show tracked tokens with
@@ -3198,26 +3199,25 @@ indexes it as a real token transfer.
   Ethereum mainnet ERC-20s taken from the CoinGecko API, with decimals verified
   on-chain and addresses EIP-55 checksummed; `TOKENS` in
   `src/shared/tokenList.js` is the authoritative set. It is bundled at build
-  time and only changes when that file is regenerated. Any token transfer
-  claiming a symbol from this list (e.g. "ETH", "USDT", "USDC") but originating
-  from an unrecognized contract address is identified as a spoof and filtered
-  from display. The fake "Ethereum" token in the attack above used symbol "ETH"
-  from contract `0xD05339f9Ea5ab9d9F03B9d57F671d2abD1F55c82`, which does not
-  match the known WETH contract — so it would be caught by this check. Detecting
-  a spoof is also what adds a contract to the fraud contract blocklist below;
-  that is the only thing that populates it. In the transaction history the check
-  is the "Hide fake tokens impersonating a known symbol" setting, on by default;
-  with it off, spoofed transfers are shown and no new blocklist entries are
-  learned from them. The send-screen token selector and the balance list apply
-  the same check unconditionally, because they decide which tokens the user can
-  act on and what the user believes they own rather than what the history
-  displays. All three surfaces read the rule from `src/shared/symbolSpoof.js`,
-  so they cannot answer the question differently. A symbol the list maps to no
-  contract at all — the native asset's labels: `"ETH"` and every network's
-  `nativeCurrency`, such as `"SepoliaETH"`, on every network — may be borne by
-  no contract, so every ERC-20 claiming it is a spoof on all three. The user's
-  real ETH balance is not an ERC-20 and is read over RPC, so the rule never sees
-  it.
+  time and only changes when that file is regenerated. On Ethereum Mainnet, a
+  token that claims a symbol from this list, such as "USDT" or "USDC", is a
+  spoof unless its contract is the listed one. The wallet hides it. The fake
+  "Ethereum" token in the attack above used symbol "ETH" from contract
+  `0xD05339f9Ea5ab9d9F03B9d57F671d2abD1F55c82`. No contract may bear "ETH", so
+  that token is a spoof. Detecting a spoof is also what adds a contract to the
+  fraud contract blocklist below; that is the only thing that populates it. In
+  the transaction history the check is the "Hide fake tokens impersonating a
+  known symbol" setting, on by default; with it off, spoofed transfers are shown
+  and no new blocklist entries are learned from them. The send-screen token
+  selector and the balance list apply the same check unconditionally, because
+  they decide which tokens the user can act on and what the user believes they
+  own rather than what the history displays. All three surfaces read the rule
+  from `src/shared/symbolSpoof.js`, so they cannot answer the question
+  differently. A symbol the list maps to no contract at all — the native asset's
+  labels: `"ETH"` and every network's `nativeCurrency`, such as `"SepoliaETH"`,
+  on every network — may be borne by no contract, so every ERC-20 claiming it is
+  a spoof on all three. The user's real ETH balance is not an ERC-20 and is read
+  over RPC, so the rule never sees it.
 
 - **Low-holder token filtering**: Token transfers from ERC-20 contracts with
   fewer than 1,000 holders are hidden from transaction history by default.
diff --git a/docs/README.md b/docs/README.md
index 9d8465f..2e26551 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -377,13 +377,15 @@ point-in-time snapshot of the highest-market-cap Ethereum mainnet ERC-20s, fixed
 at build time and updated only when a new release ships a newer snapshot. If a
 transaction or balance claims to involve a known symbol (like "ETH" or "USDT")
 but comes from an unrecognized contract, it is identified as a spoof and hidden.
-In your transaction history this is the "Hide fake tokens impersonating a known
-symbol" setting, which you can switch off; doing so also stops new entries being
-added to the fraud contract blocklist below, since detecting a spoof is what
-fills it. The send token list always applies the check. Your balances apply it
-too, with one exception: a token claiming the symbol "ETH" is not filtered
-there, so a fake "ETH" token can still show up in your balance list even though
-it is hidden from your transaction history and from the send token list.
+On Sepolia, only "ETH" and "SepoliaETH" count as known symbols, because the
+bundled list holds Ethereum Mainnet tokens. In your transaction history the
+check is the "Hide fake tokens impersonating a known symbol" setting, which you
+can switch off; doing so also stops new entries being added to the fraud
+contract blocklist below, since detecting a spoof is what fills it. The send
+token list always applies the check. Your balances apply it too, with one
+exception: a token claiming the symbol "ETH" is not filtered there, so a fake
+"ETH" token can still show up in your balance list even though it is hidden from
+your transaction history and from the send token list.
 
 **Low-holder token filtering.** Tokens with fewer than 1,000 holders are hidden
 from transaction history and the send token list, and are left out of your
diff --git a/src/popup/views/addressToken.js b/src/popup/views/addressToken.js
index 1af8e46..ce7db0e 100644
--- a/src/popup/views/addressToken.js
+++ b/src/popup/views/addressToken.js
@@ -22,7 +22,7 @@ const {
     timeAgo,
 } = require("./helpers");
 const { state, saveState, currentNetwork } = require("../../shared/state");
-const { TOKEN_BY_ADDRESS, resolveSymbol } = require("../../shared/tokenList");
+const { bundledToken, resolveSymbol } = require("../../shared/tokenList");
 const { formatUsd, getPrice } = require("../../shared/prices");
 const {
     fetchRecentTransactions,
@@ -52,7 +52,8 @@ function show() {
 
     // Determine token symbol and balance
     let symbol, amount, price;
-    const knownToken = TOKEN_BY_ADDRESS.get(tokenId.toLowerCase());
+    const chainId = currentNetwork().chainId;
+    const knownToken = bundledToken(tokenId, chainId);
     if (tokenId === "ETH") {
         symbol = nativeCurrency();
         amount = parseFloat(addr.balance || "0");
@@ -65,6 +66,7 @@ function show() {
             tokenId,
             addr.tokenBalances,
             state.trackedTokens,
+            chainId,
         );
         // null when the scale is unknown: no quantity to show, and none to
         // price. balanceLine() states that rather than printing 0.0000.
diff --git a/src/popup/views/helpers.js b/src/popup/views/helpers.js
index fc56238..c523cc0 100644
--- a/src/popup/views/helpers.js
+++ b/src/popup/views/helpers.js
@@ -313,14 +313,17 @@ function nativeCurrency() {
 // The wallets' balances hold what Blockscout reported for each token. So the
 // wallets are returned only while "Use Blockscout" is on.
 function tokenSourcesByChainId(chainId) {
-    const net = chainId ? networkByChainId(chainId) : currentNetwork();
+    const chainIdOrActive = chainId || currentNetwork().chainId;
+    const net = networkByChainId(chainIdOrActive);
     if (net && net.id === state.networkId) {
         return {
+            chainId: chainIdOrActive,
             trackedTokens: state.trackedTokens,
             wallets: state.useBlockscout ? state.wallets : [],
         };
     }
     return {
+        chainId: chainIdOrActive,
         trackedTokens: (net && state.networkTrackedTokens[net.id]) || [],
         wallets: [],
     };
@@ -351,7 +354,7 @@ function blockscoutOffTokenNoteHtml(token, chainId) {
 
 // The symbol shown for a token line, from these sources in order:
 //
-// - the bundled list
+// - the bundled list, for a token on Ethereum Mainnet
 // - the tokens the user tracks
 // - the explorer's report, while "Use Blockscout" is on
 //
diff --git a/src/popup/views/send.js b/src/popup/views/send.js
index a699562..be0796c 100644
--- a/src/popup/views/send.js
+++ b/src/popup/views/send.js
@@ -12,7 +12,7 @@ const {
     goBack,
     tokenSourcesByChainId,
 } = require("./helpers");
-const { state, currentAddress } = require("../../shared/state");
+const { state, currentAddress, currentNetwork } = require("../../shared/state");
 let ctx;
 const { getProvider } = require("../../shared/balances");
 const { resolveTokenDecimals } = require("../../shared/approvalAmount");
@@ -154,7 +154,9 @@ function renderSendTokenSelect(addr) {
         // out. Its token's own screen can still send it: there
         // state.selectedToken picks the token, not this list.
         if (isBelowOneMillionth(t.balance)) continue;
-        if (isSpoofedSymbol(t.symbol, t.address)) continue;
+        if (isSpoofedSymbol(t.symbol, t.address, currentNetwork().chainId)) {
+            continue;
+        }
         if (fraudSet.has(t.address.toLowerCase())) continue;
         // An unknown holder count does not withhold a token the user holds:
         // only a count the explorer actually reported as below the threshold
@@ -230,6 +232,7 @@ function updateSendBalance() {
             token,
             addr.tokenBalances,
             state.trackedTokens,
+            currentNetwork().chainId,
         );
         // A null balance is a holding whose scale is unknown. Saying a figure
         // for it would be a claim about the amount, so it reads as the
@@ -385,6 +388,7 @@ function init(_ctx) {
                 token,
                 addr.tokenBalances,
                 state.trackedTokens,
+                currentNetwork().chainId,
             );
             ({ tokenDecimals } = tokenBalanceAndDecimals(addr, token));
         }
diff --git a/src/shared/approvalAmount.js b/src/shared/approvalAmount.js
index 82991fe..7bbf752 100644
--- a/src/shared/approvalAmount.js
+++ b/src/shared/approvalAmount.js
@@ -29,7 +29,7 @@
 // string, and a token the user added by hand carries whatever lookupTokenInfo()
 // got back, so the accepted types are enumerated rather than coerced.
 const { toDecimals } = require("./transferAmount");
-const { TOKEN_BY_ADDRESS } = require("./tokenList");
+const { bundledToken } = require("./tokenList");
 const { isSpoofedSymbol } = require("./symbolSpoof");
 
 // Every decimals the explorer reported for this contract, across all the
@@ -53,12 +53,14 @@ function explorerDecimals(lower, wallets) {
 }
 
 // The decimals to render a token amount with, or null when nothing knows.
-// `sources` is { trackedTokens, wallets }, both shaped as they are on `state`.
+// `sources` is { chainId, trackedTokens, wallets }. `chainId` is the chain id
+// of the token's network. The bundled list is read only when that network is
+// Ethereum Mainnet. `trackedTokens` and `wallets` are shaped as on `state`.
 function resolveTokenDecimals(tokenAddress, sources) {
     const lower = (tokenAddress || "").toLowerCase();
     if (!lower) return null;
 
-    const bundled = TOKEN_BY_ADDRESS.get(lower);
+    const bundled = bundledToken(lower, sources && sources.chainId);
     if (bundled) {
         const d = toDecimals(bundled.decimals);
         if (d !== null) return d;
@@ -100,18 +102,19 @@ function explorerSymbol(lower, wallets) {
 // explorer reported: the same sources and the same precedence
 // resolveTokenDecimals() uses, so a token's name and its scale are drawn from
 // the same place and the two can no longer disagree about which sources they
-// trust. `sources` is { trackedTokens, wallets }, shaped as on `state`.
+// trust. `sources` is as for resolveTokenDecimals().
 //
 // A tracked or explorer-reported symbol is attacker-influenced text, so it is
-// held to the spoof rule (symbolSpoof.js): a candidate that wears a bundled or
-// native ticker from a contract not entitled to it is refused and the next
-// source tried, so resolving a symbol never becomes a new way to claim a known
-// ticker. The bundled list is the wallet's own data and is trusted as it is.
+// held to the spoof rule (symbolSpoof.js): a candidate that the rule calls a
+// spoof is refused and the next source tried, so resolving a symbol never
+// becomes a new way to claim a known ticker. The bundled list is the wallet's
+// own data and is trusted as it is.
 function resolveTokenSymbol(tokenAddress, sources) {
     const lower = (tokenAddress || "").toLowerCase();
     if (!lower) return null;
 
-    const bundled = TOKEN_BY_ADDRESS.get(lower);
+    const chainId = sources && sources.chainId;
+    const bundled = bundledToken(lower, chainId);
     if (bundled && bundled.symbol) return bundled.symbol;
 
     const tracked = ((sources && sources.trackedTokens) || []).find(
@@ -123,7 +126,7 @@ function resolveTokenSymbol(tokenAddress, sources) {
     if (reported) candidates.push(reported);
 
     for (const symbol of candidates) {
-        if (!isSpoofedSymbol(symbol, tokenAddress)) return symbol;
+        if (!isSpoofedSymbol(symbol, tokenAddress, chainId)) return symbol;
     }
     return null;
 }
diff --git a/src/shared/balances.js b/src/shared/balances.js
index fe4e4bc..9ed86fd 100644
--- a/src/shared/balances.js
+++ b/src/shared/balances.js
@@ -17,7 +17,7 @@ const { ERC20_ABI } = require("./constants");
 const { NETWORKS } = require("./networks");
 const { log, debugFetch, urlOrigin } = require("./log");
 const { deriveAddressFromXpub } = require("./wallet");
-const { TOKEN_BY_ADDRESS } = require("./tokenList");
+const { bundledToken } = require("./tokenList");
 const { LOW_HOLDER_THRESHOLD, parseHoldersCount } = require("./holders");
 const { isSpoofedSymbol } = require("./symbolSpoof");
 const { toDecimals } = require("./transferAmount");
@@ -106,6 +106,9 @@ function rawUnits(value) {
 // balance is read through the RPC endpoint instead, and its row here gives that
 // entry its holder count and `decimals` (fetchTrackedTokenBalances()).
 //
+// `chainId` is the chain id of the network `blockscoutUrl` serves. The known
+// token list is used only when that network is Ethereum Mainnet.
+//
 // `decimals` and `balance` are each null when the answer is unknown, the same
 // way `holders` already is. Absence is never filled in here: this is the
 // upstream of every screen that displays a token amount, so a value invented
@@ -117,6 +120,7 @@ async function fetchTokenBalances(
     address,
     blockscoutUrl,
     trackedTokens,
+    chainId,
     signal,
 ) {
     if (!(await storedSettingIsOn("useBlockscout"))) return [];
@@ -175,7 +179,10 @@ async function fetchTokenBalances(
             // either way: copying another source into it would make
             // explorerDecimals()'s disagreement check compare something other
             // than explorer values.
-            const known = resolveTokenDecimals(tokenAddr, { trackedTokens });
+            const known = resolveTokenDecimals(tokenAddr, {
+                chainId,
+                trackedTokens,
+            });
             const scale = known !== null ? known : decimals;
             // null is a holding of an amount that cannot be stated, which is
             // not the same as a holding of zero, and must never render as one.
@@ -191,7 +198,7 @@ async function fetchTokenBalances(
             // through to the views, where the two low-holder filters treat
             // an unknown count as "do not judge" rather than as zero.
             const holders = parseHoldersCount(item.token.holders_count);
-            const isKnown = TOKEN_BY_ADDRESS.has(tokenAddr);
+            const isKnown = bundledToken(tokenAddr, chainId) !== null;
             const isTracked = trackedSet.has(tokenAddr);
             const hasEnoughHolders = holders >= LOW_HOLDER_THRESHOLD;
 
@@ -202,7 +209,9 @@ async function fetchTokenBalances(
             // Every row here is an ERC-20 the explorer reported, so it has a
             // contract address; the native ETH balance is fetched over RPC in
             // refreshBalances and never passes through this loop.
-            if (isSpoofedSymbol(item.token.symbol, tokenAddr)) continue;
+            if (isSpoofedSymbol(item.token.symbol, tokenAddr, chainId)) {
+                continue;
+            }
 
             balances.push({
                 address: item.token.address_hash,
@@ -249,17 +258,18 @@ async function fetchTokenBalances(
 // zero from the tracked list. A token whose symbol the spoof rule refuses gets
 // no entry either, as in fetchTokenBalances().
 //
-// `signal` is as for fetchTokenBalances().
+// `chainId` and `signal` are as for fetchTokenBalances().
 async function fetchTrackedTokenBalances(
     provider,
     address,
     trackedTokens,
     previous,
     explorerRequest,
+    chainId,
     signal,
 ) {
     const listed = trackedTokens.filter(
-        (token) => !isSpoofedSymbol(token.symbol, token.address),
+        (token) => !isSpoofedSymbol(token.symbol, token.address, chainId),
     );
     // Each token's balanceOf answer, or null where it failed.
     const balances = await Promise.all(
@@ -301,7 +311,7 @@ async function fetchTrackedTokenBalances(
         if (raw === 0n) return;
         const entry = entryIn(reported);
         const decimals = entry ? entry.decimals : null;
-        const known = resolveTokenDecimals(lower, { trackedTokens });
+        const known = resolveTokenDecimals(lower, { chainId, trackedTokens });
         const scale = known !== null ? known : decimals;
         rows.push({
             address: token.address,
@@ -330,6 +340,7 @@ async function refreshBalances(
 ) {
     log.debugf("refreshBalances start, rpc:", urlOrigin(rpcUrl));
     const provider = getProvider(rpcUrl, networkId);
+    const { chainId } = requireNetworkId(networkId);
     const tracked = trackedTokens || [];
     const trackedSet = new Set(tracked.map((t) => t.address.toLowerCase()));
     const updates = [];
@@ -393,6 +404,7 @@ async function refreshBalances(
                 addr.address,
                 blockscoutUrl,
                 tracked,
+                chainId,
                 signal,
             );
             updates.push(
@@ -403,6 +415,7 @@ async function refreshBalances(
                         tracked,
                         previous,
                         explorerRequest,
+                        chainId,
                         signal,
                     ),
                     explorerRequest,
diff --git a/src/shared/symbolSpoof.js b/src/shared/symbolSpoof.js
index c2d5947..2c005f0 100644
--- a/src/shared/symbolSpoof.js
+++ b/src/shared/symbolSpoof.js
@@ -19,7 +19,8 @@
 // them hid the other one's holders' money (issue #276).  Membership, not
 // equality, is therefore the question — but it is the same question, asked of
 // a table that can now state the truth.  Every address in a set is one the
-// wallet ships as a real token; a contract outside the set is still a spoof.
+// wallet ships as a real token on Ethereum Mainnet.  On mainnet, a contract
+// outside the set is still a spoof.
 //
 // The symbol is attacker-controlled — it is whatever the ERC-20 contract
 // returns — so the lookup is done on a normalized form (issue #260): the
@@ -27,6 +28,7 @@
 // since that is what the user acts on.
 
 const { KNOWN_SYMBOLS } = require("./tokenList");
+const { NETWORKS } = require("./networks");
 
 // Ethereum addresses are case-insensitive: EIP-55 mixed case is a checksum
 // over the address, not part of its identity.
@@ -93,18 +95,24 @@ function normalizeSymbol(symbol) {
 }
 
 // True when a token bearing `symbol` from contract `contractAddress` is
-// impersonating a known symbol.
+// impersonating a known symbol. `chainId` is the chain id of the token's
+// network.
+//
+// The native asset's labels are known symbols on every network. The bundled
+// list's symbols are known symbols only on Ethereum Mainnet, because the list
+// holds mainnet contracts.
 //
 // An empty contract address is the native asset, which is never a spoof:
 // this is what keeps the user's real ETH out of the rule, and it holds for
 // any symbol that becomes null-mapped later, not just for ETH.
-function isSpoofedSymbol(symbol, contractAddress) {
+function isSpoofedSymbol(symbol, contractAddress, chainId) {
     const contract = normalizeAddress(contractAddress);
     if (!contract) return false;
     const sym = normalizeSymbol(symbol);
     if (!KNOWN_SYMBOLS.has(sym)) return false;
     const legit = KNOWN_SYMBOLS.get(sym);
     if (legit === null) return true;
+    if (chainId !== NETWORKS.mainnet.chainId) return false;
     return !legit.has(contract);
 }
 
diff --git a/src/shared/tokenList.js b/src/shared/tokenList.js
index 33ccbca..d02c123 100644
--- a/src/shared/tokenList.js
+++ b/src/shared/tokenList.js
@@ -3953,6 +3953,15 @@ for (const t of TOKENS) {
     TOKEN_BY_ADDRESS.set(t.address.toLowerCase(), t);
 }
 
+// The bundled list's entry for the contract at `address` on the network with
+// chain id `chainId`, or null. The list holds Ethereum Mainnet contracts only.
+// A contract at the same address on another network is another token, so any
+// other chain id gets null.
+function bundledToken(address, chainId) {
+    if (chainId !== NETWORKS.mainnet.chainId) return null;
+    return TOKEN_BY_ADDRESS.get((address || "").toLowerCase()) || null;
+}
+
 // Build a map of symbol (uppercased) -> the set of contract addresses
 // (lowercased) that legitimately bear it.  Used for spoofed-symbol detection.
 // "ETH" maps to null: the native asset has no contract, so no contract may
@@ -3969,7 +3978,8 @@ for (const t of TOKENS) {
 // hides from the balance list, the history and the send selector at its own
 // address, so the user cannot spend it (issue #276).  Naming every address
 // that bears the symbol is the only shape that says what is true; it does not
-// loosen the rule, because a contract outside the set is still a spoof.
+// loosen the rule.  On Ethereum Mainnet, a contract outside the set is still a
+// spoof.
 const KNOWN_SYMBOLS = new Map();
 KNOWN_SYMBOLS.set("ETH", null);
 for (const network of Object.values(NETWORKS)) {
@@ -3988,14 +3998,15 @@ for (const t of TOKENS) {
     }
 }
 
-// Resolve a token symbol from multiple sources, never returning "?".
-function resolveSymbol(tokenAddress, tokenBalances, trackedTokens) {
+// Resolve a token symbol from multiple sources, never returning "?". The token
+// is a contract on the network with chain id `chainId`.
+function resolveSymbol(tokenAddress, tokenBalances, trackedTokens, chainId) {
     const lower = (tokenAddress || "").toLowerCase();
     const tb = (tokenBalances || []).find(
         (t) => t.address.toLowerCase() === lower,
     );
     if (tb && tb.symbol) return tb.symbol;
-    const known = TOKEN_BY_ADDRESS.get(lower);
+    const known = bundledToken(lower, chainId);
     if (known && known.symbol) return known.symbol;
     const tracked = (trackedTokens || []).find(
         (t) => t.address.toLowerCase() === lower,
@@ -4012,5 +4023,6 @@ module.exports = {
     USD_PRICE_FEEDS,
     PRICE_FEED_BY_ADDRESS,
     getTopTokens,
+    bundledToken,
     resolveSymbol,
 };
diff --git a/src/shared/transactions.js b/src/shared/transactions.js
index bf3e22b..522458c 100644
--- a/src/shared/transactions.js
+++ b/src/shared/transactions.js
@@ -8,7 +8,7 @@
 
 const { formatEther, formatUnits } = require("ethers");
 const { log, debugFetch } = require("./log");
-const { TOKEN_BY_ADDRESS } = require("./tokenList");
+const { bundledToken } = require("./tokenList");
 const { parseHoldersCount, isLowHolderCount } = require("./holders");
 const { isSpoofedSymbol } = require("./symbolSpoof");
 const { nativeCurrencyByChainId } = require("./networks");
@@ -47,7 +47,7 @@ function parseTx(tx, addrLower, chainId) {
     let direction = normalizeAddress(from) === addrLower ? "sent" : "received";
     let directionLabel = direction === "sent" ? "Sent" : "Received";
     if (toIsContract && method && method !== "transfer") {
-        const token = TOKEN_BY_ADDRESS.get(normalizeAddress(to));
+        const token = bundledToken(to, chainId);
         if (token) {
             symbol = token.symbol;
         }
@@ -317,7 +317,10 @@ function filterTransactions(txs, filters = {}) {
         const contract = normalizeAddress(tx.contractAddress);
 
         // Filter spoofed known symbols and record the fraud contract
-        if (hideSpoofed && isSpoofedSymbol(tx.symbol, tx.contractAddress)) {
+        if (
+            hideSpoofed &&
+            isSpoofedSymbol(tx.symbol, tx.contractAddress, tx.chainId)
+        ) {
             if (contract && !fraudSet.has(contract)) {
                 fraudSet.add(contract);
                 newFraud.push(contract);
diff --git a/src/shared/uniswap.js b/src/shared/uniswap.js
index 6e140b7..4966139 100644
--- a/src/shared/uniswap.js
+++ b/src/shared/uniswap.js
@@ -452,8 +452,8 @@ const ADDRESS_THIS = "0x0000000000000000000000000000000000000002";
 // `decimals` is null when nothing knows this token's scale. It is not
 // defaulted to 18: the swap lines land on the same approval screen as the
 // ERC-20 line, and a scale guessed there is what showed a 1,000 USDT swap as
-// 0.000000000001. `sources` is { trackedTokens, wallets }, shaped as they are
-// on `state`; resolveTokenDecimals() reads the bundled list, then those.
+// 0.000000000001. `sources` is as for resolveTokenDecimals(), which reads the
+// bundled list on Ethereum Mainnet, then the tracked tokens and the wallets.
 //
 // A null `address` means UNDETERMINED — the calldata named no currency for
 // that side — and is refused rather than named. It is not native ETH: Uniswap
@@ -1240,6 +1240,9 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
     const release = routerRelease(toAddress, chainId);
     if (release === null) return null;
     const { commandTypeMask, commands, allowRevert } = release;
+    // The swap's tokens are contracts on the network with `chainId`, so they
+    // are named and scaled for that network.
+    const tokenSources = { ...sources, chainId };
     try {
         const parsed = ROUTER_IFACE.parseTransaction({ data });
         if (!parsed) return null;
@@ -2208,11 +2211,11 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // Any other output keeps its own token and figure: a swap that pays
         // its WETH to the user and then unwraps receives WETH, and one that
         // buys USDC and then unwraps the WETH it did not spend receives USDC.
-        const inInfo = tokenInfo(inputToken, sources);
+        const inInfo = tokenInfo(inputToken, tokenSources);
         const outInfo =
             outputUnwrapped || (hasUnwrapWeth && !outputEstablished)
                 ? { symbol: "ETH", decimals: 18, address: null }
-                : tokenInfo(outputToken, sources);
+                : tokenInfo(outputToken, tokenSources);
 
         const inSymbol = inInfo.symbol;
         const outSymbol = outInfo.symbol;
@@ -2337,13 +2340,19 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             details.push({
                 label: "Moved from the sender",
                 value: present(s.amount)
-                    ? spentText(s.amount, tokenInfo(s.token, sources), s.atMost)
-                          .display
+                    ? spentText(
+                          s.amount,
+                          tokenInfo(s.token, tokenSources),
+                          s.atMost,
+                      ).display
                     : UNDECODED_CURRENCY,
             });
             if (present(s.token)) {
                 details.push(
-                    tokenMovedLine("Token moved", tokenInfo(s.token, sources)),
+                    tokenMovedLine(
+                        "Token moved",
+                        tokenInfo(s.token, tokenSources),
+                    ),
                 );
                 details.push({
                     label: "Moved to",
@@ -2355,7 +2364,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
         // What each PERMIT2_TRANSFER_FROM moves: its amount, its token and
         // where it goes, an address on a line of its own.
         for (const m of movedFromSender) {
-            const info = permit2TokenInfo(m.token, sources);
+            const info = permit2TokenInfo(m.token, tokenSources);
             details.push({
                 label: "Moved from the sender",
                 value: amountText(m.amount, info).display,
@@ -2390,7 +2399,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
                 });
                 continue;
             }
-            const info = permit2TokenInfo(p.token, sources);
+            const info = permit2TokenInfo(p.token, tokenSources);
             details.push({
                 label: "Permit2 allowance",
                 value:
@@ -2456,7 +2465,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             paidTo.push({ label: "Paid to", value: PAID_TO_BRIDGE });
         }
         for (const m of movedIntoRouter) {
-            const info = permit2TokenInfo(m.token, sources);
+            const info = permit2TokenInfo(m.token, tokenSources);
             paidTo.push({
                 label: "Paid to",
                 value:
@@ -2481,7 +2490,7 @@ function decode(data, toAddress, chainId, sources, fromAddress) {
             paidTo.push(
                 tokenMovedLine(
                     "Token moved into the router",
-                    tokenInfo(getAddress(token), sources),
+                    tokenInfo(getAddress(token), tokenSources),
                 ),
             );
         }
diff --git a/tests/approvalAmount.test.js b/tests/approvalAmount.test.js
index 2825d12..229f00a 100644
--- a/tests/approvalAmount.test.js
+++ b/tests/approvalAmount.test.js
@@ -90,9 +90,11 @@ beforeEach(() => {
 });
 
 describe("resolveTokenDecimals", () => {
+    // The bundled list is read only for a token on Ethereum Mainnet.
     test("prefers the bundled list", () => {
         state.trackedTokens = [{ address: USDC, symbol: "USDC", decimals: 2 }];
-        expect(resolveTokenDecimals(USDC, state)).toBe(6);
+        const sources = { chainId: "0x1", trackedTokens: state.trackedTokens };
+        expect(resolveTokenDecimals(USDC, sources)).toBe(6);
     });
 
     test("reads a token the user tracks", () => {
@@ -124,7 +126,8 @@ describe("resolveTokenDecimals", () => {
     // answers 0 is used rather than fallen past like the unusable entry above.
     test("uses a bundled scale of zero", () => {
         state.trackedTokens = [{ address: SLP, symbol: "SLP", decimals: 18 }];
-        expect(resolveTokenDecimals(SLP, state)).toBe(0);
+        const sources = { chainId: "0x1", trackedTokens: state.trackedTokens };
+        expect(resolveTokenDecimals(SLP, sources)).toBe(0);
     });
 
     test("uses a tracked scale of zero", () => {
diff --git a/tests/approvalBundledListSepolia.test.js b/tests/approvalBundledListSepolia.test.js
new file mode 100644
index 0000000..5f332c4
--- /dev/null
+++ b/tests/approvalBundledListSepolia.test.js
@@ -0,0 +1,169 @@
+// The approval screen for a site's Sepolia transfer of the contract at USDC's
+// mainnet address, while Sepolia is active.
+//
+// The bundled token list holds Ethereum Mainnet contracts. The contract at the
+// same address on Sepolia is another token, but the screen named it USDC and
+// scaled its amount at USDC's decimals
+// (https://git.eeqj.de/sneak/AutistMask/issues/632). The bundled list now names
+// a token only on Ethereum Mainnet. The same screen for a mainnet transfer of
+// USDC, while Sepolia is active, still names USDC.
+//
+// Driven through the real approval screen, against the minimal DOM stub
+// tests/approvalTokenNetwork.test.js uses.
+
+globalThis.chrome = {
+    storage: { local: { get: async () => ({}), set: async () => {} } },
+};
+
+const { Interface } = require("ethers");
+const { state } = require("../src/shared/state");
+const { NETWORKS } = require("../src/shared/networks");
+const approval = require("../src/popup/views/approval");
+
+const FROM = "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266";
+const RECIPIENT = "0x711e691962E5c054b78071C789A0C8CE657377aD";
+// USDC's address on Ethereum Mainnet, where the bundled list names it.
+const USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
+
+// FROM sends 1234500000 base units to RECIPIENT.
+const TRANSFER_DATA = new Interface([
+    "function transfer(address to, uint256 amount)",
+]).encodeFunctionData("transfer", [RECIPIENT, 1234500000n]);
+
+function makeElement(id) {
+    const classes = new Set();
+    const el = {
+        id,
+        textContent: "",
+        value: "",
+        innerHTML: "",
+        disabled: false,
+        style: {},
+        dataset: {},
+        listeners: {},
+        classList: {
+            add: (...names) => names.forEach((n) => classes.add(n)),
+            remove: (...names) => names.forEach((n) => classes.delete(n)),
+            contains: (n) => classes.has(n),
+            toggle: (n, force) => {
+                const on = force === undefined ? !classes.has(n) : force;
+                if (on) classes.add(n);
+                else classes.delete(n);
+                return on;
+            },
+        },
+        addEventListener: (name, fn) => {
+            el.listeners[name] = el.listeners[name] || [];
+            el.listeners[name].push(fn);
+        },
+        querySelectorAll: () => [],
+        appendChild: () => {},
+    };
+    // Views reach for .parentElement to hide whole sections.
+    Object.defineProperty(el, "parentElement", {
+        get: () => node(id + "-parent"),
+    });
+    return el;
+}
+
+function makeDocument() {
+    const els = new Map();
+    return {
+        getElementById(id) {
+            // The debug banner is created on demand by helpers.js; absent
+            // is the state a non-debug, non-testnet popup is in.
+            if (id === "debug-banner") return null;
+            if (!els.has(id)) els.set(id, makeElement(id));
+            return els.get(id);
+        },
+        createElement: () => makeElement("created"),
+        body: { prepend: () => {} },
+    };
+}
+
+function node(id) {
+    return globalThis.document.getElementById(id);
+}
+
+// One line of the decoded details: its label and what is drawn under it.
+function decodedLine(label) {
+    return node("approve-tx-decoded-details")
+        .innerHTML.split('<div class="mb-2">')
+        .find((line) =>
+            line.startsWith(`<div class="text-muted">${label}</div>`),
+        );
+}
+
+// Open the approval screen, with Sepolia active, for the site's transaction
+// sending TRANSFER_DATA to the contract at USDC's address on the network with
+// chain id `chainId`.
+async function showTransfer(chainId) {
+    globalThis.document = makeDocument();
+    globalThis.window = { location: { search: "" }, close: () => {} };
+    globalThis.chrome.runtime = {
+        connect: () => ({ postMessage: () => {} }),
+        sendMessage: (msg, reply) => {
+            if (!reply) return;
+            reply({
+                type: "tx",
+                origin: "https://dapp.example",
+                isPhishingDomain: false,
+                approvedFrom: FROM,
+                approvedTx: {
+                    type: 2,
+                    from: FROM,
+                    chainId,
+                    nonce: "0x7",
+                    gasLimit: "0x30d40",
+                    maxPriorityFeePerGas: "0x3b9aca00",
+                    maxFeePerGas: "0x77359400",
+                    to: USDC,
+                    value: "0x0",
+                    data: TRANSFER_DATA,
+                    accessList: [],
+                },
+            });
+        },
+    };
+    state.networkId = "sepolia";
+    state.trackedTokens = [];
+    state.networkTrackedTokens = {};
+    state.activeAddress = FROM;
+    state.wallets = [
+        {
+            type: "hd",
+            name: "Wallet 1",
+            xpub: "xpub-wallet-1",
+            encryptedSecret: "encrypted-secret-1",
+            nextIndex: 1,
+            addresses: [
+                { address: FROM, index: 0, balance: "0", tokenBalances: [] },
+            ],
+        },
+    ];
+    state.currentView = null;
+    approval.init({});
+    await approval.show(1);
+}
+
+test("names no token, and states the amount in base units", async () => {
+    await showTransfer(NETWORKS.sepolia.chainId);
+    expect(state.currentView).toBe("approve-tx");
+    expect(node("approve-tx-to").innerHTML).not.toContain("USDC");
+    expect(decodedLine("Token")).toContain(
+        '<div class="font-bold">Unknown token</div>',
+    );
+    expect(decodedLine("Amount")).toContain(
+        '<div class="font-bold">1234500000 base units (decimals unknown)</div>',
+    );
+});
+
+// A transaction is named for its own network, not the active one.
+test("a mainnet transfer of USDC is still named and scaled as USDC", async () => {
+    await showTransfer(NETWORKS.mainnet.chainId);
+    expect(state.currentView).toBe("approve-tx");
+    expect(decodedLine("Token")).toContain('<div class="font-bold">USDC</div>');
+    expect(decodedLine("Amount")).toContain(
+        '<div class="font-bold">1234.5000 USDC</div>',
+    );
+});
diff --git a/tests/bundledListScreens.test.js b/tests/bundledListScreens.test.js
new file mode 100644
index 0000000..e876687
--- /dev/null
+++ b/tests/bundledListScreens.test.js
@@ -0,0 +1,81 @@
+// The token screen, the Send screen and the confirmation screen for the
+// contract at USDC's mainnet address. No address holds it and the user does
+// not track it, so only the bundled token list can name it.
+//
+// The bundled token list holds Ethereum Mainnet contracts, so these screens
+// name the token from it on Ethereum Mainnet only
+// (https://git.eeqj.de/sneak/AutistMask/issues/632). Driven through the real
+// popup over a stored profile.
+
+const {
+    bootPopup,
+    cleanupPopup,
+    unversionedValidProfile,
+} = require("./support/popupBoot");
+
+const USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
+const RECIPIENT = "0x711e691962E5c054b78071C789A0C8CE657377aD";
+
+afterEach(() => {
+    cleanupPopup();
+});
+
+// The popup reopened onto AddressToken for USDC's address, on `networkId`.
+function bootOnToken(networkId) {
+    return bootPopup(
+        unversionedValidProfile({
+            networkId,
+            currentView: "address-token",
+            viewStack: ["main", "address"],
+            selectedWallet: 0,
+            selectedAddress: 0,
+            selectedToken: USDC,
+        }),
+    );
+}
+
+// AddressToken's Send, then Review for 1 token to RECIPIENT.
+async function reviewSend(boot) {
+    await boot.click("btn-address-token-send");
+    expect(boot.visibleViews()).toEqual(["send"]);
+    boot.node("send-to").value = RECIPIENT;
+    boot.node("send-amount").value = "1";
+    await boot.click("btn-send-review");
+    expect(boot.visibleViews()).toEqual(["confirm-tx"]);
+}
+
+describe("on Ethereum Mainnet, the bundled list names the token", () => {
+    test("on the token screen", async () => {
+        const boot = await bootOnToken("mainnet");
+        expect(boot.visibleViews()).toEqual(["address-token"]);
+        expect(boot.text("address-token-title")).toContain("USDC");
+        const info = boot.node("address-token-contract-info").innerHTML;
+        expect(info).toContain(
+            '<span class="text-muted">Decimals:</span> 6</div>',
+        );
+    });
+
+    test("on the Send screen and the confirmation screen", async () => {
+        const boot = await bootOnToken("mainnet");
+        await reviewSend(boot);
+        expect(boot.text("send-balance")).toContain("USDC");
+        expect(boot.text("confirm-amount")).toContain("USDC");
+    });
+});
+
+describe("with Sepolia active, the bundled list does not name the token", () => {
+    test("on the token screen", async () => {
+        const boot = await bootOnToken("sepolia");
+        expect(boot.visibleViews()).toEqual(["address-token"]);
+        expect(boot.text("address-token-title")).not.toContain("USDC");
+        const info = boot.node("address-token-contract-info").innerHTML;
+        expect(info).not.toContain("Decimals:");
+    });
+
+    test("on the Send screen and the confirmation screen", async () => {
+        const boot = await bootOnToken("sepolia");
+        await reviewSend(boot);
+        expect(boot.text("send-balance")).not.toContain("USDC");
+        expect(boot.text("confirm-amount")).not.toContain("USDC");
+    });
+});
diff --git a/tests/fabricatedDecimals.test.js b/tests/fabricatedDecimals.test.js
index 30a419d..7c2f8bb 100644
--- a/tests/fabricatedDecimals.test.js
+++ b/tests/fabricatedDecimals.test.js
@@ -111,13 +111,15 @@ function respondWith(items) {
 }
 
 // Fetch and place the result exactly where refreshBalances() places it, so the
-// approval screens read what a real refresh would have left on state.
+// approval screens read what a real refresh on Ethereum Mainnet would have
+// left on state.
 async function fetchOnto(items, trackedTokens = []) {
     respondWith(items);
     const balances = await fetchTokenBalances(
         HOLDER,
         BLOCKSCOUT,
         trackedTokens,
+        "0x1",
     );
     state.trackedTokens = trackedTokens;
     state.wallets = [
diff --git a/tests/holders.test.js b/tests/holders.test.js
index 818eb64..be7effe 100644
--- a/tests/holders.test.js
+++ b/tests/holders.test.js
@@ -192,7 +192,13 @@ describe("the balance-list spam gate", () => {
                 },
             }),
         ]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        // On Ethereum Mainnet, the only network the known-token list covers.
+        const balances = await fetchTokenBalances(
+            HOLDER,
+            BLOCKSCOUT,
+            [],
+            "0x1",
+        );
         expect(balances).toHaveLength(1);
         expect(balances[0].holders).toBeNull();
     });
diff --git a/tests/resolveTokenSymbol.test.js b/tests/resolveTokenSymbol.test.js
index d093e87..ef97e49 100644
--- a/tests/resolveTokenSymbol.test.js
+++ b/tests/resolveTokenSymbol.test.js
@@ -67,13 +67,15 @@ beforeEach(() => {
 });
 
 describe("resolveTokenSymbol", () => {
+    // The bundled list is read only for a token on Ethereum Mainnet.
     test("reads the bundled list", () => {
-        expect(resolveTokenSymbol(USDC, state)).toBe("USDC");
+        expect(resolveTokenSymbol(USDC, { chainId: "0x1" })).toBe("USDC");
     });
 
     test("prefers the bundled list over a tracked entry", () => {
         state.trackedTokens = [{ address: USDC, symbol: "NOTUSDC" }];
-        expect(resolveTokenSymbol(USDC, state)).toBe("USDC");
+        const sources = { chainId: "0x1", trackedTokens: state.trackedTokens };
+        expect(resolveTokenSymbol(USDC, sources)).toBe("USDC");
     });
 
     test("reads a token the user tracks", () => {
@@ -104,7 +106,19 @@ describe("resolveTokenSymbol", () => {
     test("rejects a tracked entry claiming a bundled ticker it is not", () => {
         // NOVEL_TOKEN is not the real USDC contract, so it may not wear USDC.
         state.trackedTokens = [{ address: NOVEL_TOKEN, symbol: "USDC" }];
-        expect(resolveTokenSymbol(NOVEL_TOKEN, state)).toBeNull();
+        const sources = { chainId: "0x1", trackedTokens: state.trackedTokens };
+        expect(resolveTokenSymbol(NOVEL_TOKEN, sources)).toBeNull();
+    });
+
+    // The bundled list holds mainnet contracts, so on Sepolia any contract may
+    // carry one of its symbols.
+    test("on Sepolia, reads a tracked entry carrying a bundled ticker", () => {
+        state.trackedTokens = [{ address: NOVEL_TOKEN, symbol: "USDC" }];
+        const sources = {
+            chainId: "0xaa36a7",
+            trackedTokens: state.trackedTokens,
+        };
+        expect(resolveTokenSymbol(NOVEL_TOKEN, sources)).toBe("USDC");
     });
 
     test("rejects an explorer entry claiming the native ETH ticker", () => {
diff --git a/tests/symbolSpoof.test.js b/tests/symbolSpoof.test.js
index fc5fd82..d116526 100644
--- a/tests/symbolSpoof.test.js
+++ b/tests/symbolSpoof.test.js
@@ -72,6 +72,11 @@ const {
 const { renderSendTokenSelect } = require("../src/popup/views/send");
 const { state } = require("../src/shared/state");
 const { debugFetch } = require("../src/shared/log");
+const { NETWORKS } = require("../src/shared/networks");
+
+// The bundled list's symbols are known symbols only on Ethereum Mainnet.
+const MAINNET = NETWORKS.mainnet.chainId;
+const SEPOLIA = NETWORKS.sepolia.chainId;
 
 // The fake "Ethereum" token with symbol "ETH" from the attack documented in
 // README.md, given a holder count high enough to clear every other filter so
@@ -116,14 +121,29 @@ describe("the shared rule", () => {
     });
 
     test("a known symbol from its own contract is not a spoof", () => {
-        expect(isSpoofedSymbol("USDC", USDC_CONTRACT)).toBe(false);
-        expect(isSpoofedSymbol("usdc", USDC_CONTRACT.toUpperCase())).toBe(
-            false,
-        );
+        expect(isSpoofedSymbol("USDC", USDC_CONTRACT, MAINNET)).toBe(false);
+        expect(
+            isSpoofedSymbol("usdc", USDC_CONTRACT.toUpperCase(), MAINNET),
+        ).toBe(false);
     });
 
     test("a known symbol from another contract is a spoof", () => {
-        expect(isSpoofedSymbol("USDC", FAKE_ETH_CONTRACT)).toBe(true);
+        expect(isSpoofedSymbol("USDC", FAKE_ETH_CONTRACT, MAINNET)).toBe(true);
+    });
+
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+    // mainnet contracts, so on Sepolia any contract may carry one of its
+    // symbols.
+    test("on Sepolia, a bundled symbol from any contract is not a spoof", () => {
+        expect(isSpoofedSymbol("USDC", FAKE_ETH_CONTRACT, SEPOLIA)).toBe(false);
+        expect(isSpoofedSymbol("USDC", USDC_CONTRACT, SEPOLIA)).toBe(false);
+    });
+
+    test("on Sepolia, the native asset's labels are still reserved", () => {
+        expect(isSpoofedSymbol("ETH", FAKE_ETH_CONTRACT, SEPOLIA)).toBe(true);
+        expect(isSpoofedSymbol("SepoliaETH", FAKE_ETH_CONTRACT, SEPOLIA)).toBe(
+            true,
+        );
     });
 
     test("a symbol that is not in the table is not judged here", () => {
@@ -164,7 +184,9 @@ describe("the shared rule: symbols that render as a known symbol", () => {
     test("ASCII padding does not buy a pass", () => {
         expect(isSpoofedSymbol(" ETH ", FAKE_ETH_CONTRACT)).toBe(true);
         expect(isSpoofedSymbol("\tETH\n", FAKE_ETH_CONTRACT)).toBe(true);
-        expect(isSpoofedSymbol("  usdc  ", FAKE_ETH_CONTRACT)).toBe(true);
+        expect(isSpoofedSymbol("  usdc  ", FAKE_ETH_CONTRACT, MAINNET)).toBe(
+            true,
+        );
     });
 
     test("non-breaking and other Unicode spaces do not either", () => {
@@ -243,7 +265,9 @@ describe("the shared rule: symbols that render as a known symbol", () => {
 
     test("compatibility forms fold onto the symbol they imitate", () => {
         expect(isSpoofedSymbol(FULLWIDTH_ETH, FAKE_ETH_CONTRACT)).toBe(true);
-        expect(isSpoofedSymbol(FULLWIDTH_USDC, FAKE_ETH_CONTRACT)).toBe(true);
+        expect(
+            isSpoofedSymbol(FULLWIDTH_USDC, FAKE_ETH_CONTRACT, MAINNET),
+        ).toBe(true);
     });
 
     // The two knowingly open classes, asserted here so that the boundary is
@@ -271,8 +295,10 @@ describe("the shared rule: symbols that render as a known symbol", () => {
     });
 
     test("a genuine contract still bears its own padded symbol", () => {
-        expect(isSpoofedSymbol(" USDC ", USDC_CONTRACT)).toBe(false);
-        expect(isSpoofedSymbol(ZWSP + "WETH", WETH_CONTRACT)).toBe(false);
+        expect(isSpoofedSymbol(" USDC ", USDC_CONTRACT, MAINNET)).toBe(false);
+        expect(isSpoofedSymbol(ZWSP + "WETH", WETH_CONTRACT, MAINNET)).toBe(
+            false,
+        );
     });
 
     // Normalization must not invent a match.  Interior ASCII whitespace is
@@ -296,7 +322,7 @@ describe("the shared rule: symbols that render as a known symbol", () => {
             expect(symbol).toMatch(/^[!-~]+$/);
             if (addresses === null) continue;
             for (const address of addresses) {
-                expect(isSpoofedSymbol(symbol, address)).toBe(false);
+                expect(isSpoofedSymbol(symbol, address, MAINNET)).toBe(false);
             }
         }
     });
@@ -317,7 +343,7 @@ describe("the shared rule: symbols that render as a known symbol", () => {
 describe("the shipped token list", () => {
     test("no bundled token is filtered at its own address", () => {
         const filtered = TOKENS.filter((t) =>
-            isSpoofedSymbol(t.symbol, t.address),
+            isSpoofedSymbol(t.symbol, t.address, MAINNET),
         ).map((t) => t.symbol + " @ " + t.address);
         expect(filtered).toEqual([]);
     });
@@ -360,7 +386,9 @@ describe("the shipped token list", () => {
         expect(shared.length).toBeGreaterThan(0);
         for (const [, list] of shared) {
             for (const t of list) {
-                expect(isSpoofedSymbol(t.symbol, t.address)).toBe(false);
+                expect(isSpoofedSymbol(t.symbol, t.address, MAINNET)).toBe(
+                    false,
+                );
             }
         }
     });
@@ -404,7 +432,7 @@ describe("the shipped token list", () => {
                 [...addresses].sort(),
             );
             for (const address of addresses) {
-                expect(isSpoofedSymbol(symbol, address)).toBe(false);
+                expect(isSpoofedSymbol(symbol, address, MAINNET)).toBe(false);
             }
         }
     });
@@ -421,7 +449,9 @@ describe("the shipped token list", () => {
         }
         for (const [symbol, list] of bySymbol) {
             if (list.length < 2) continue;
-            expect(isSpoofedSymbol(symbol, FAKE_ETH_CONTRACT)).toBe(true);
+            expect(isSpoofedSymbol(symbol, FAKE_ETH_CONTRACT, MAINNET)).toBe(
+                true,
+            );
         }
     });
 });
@@ -506,10 +536,40 @@ describe("surface 2: the Send token selector", () => {
     }
 
     beforeEach(() => {
+        state.networkId = "mainnet";
         state.fraudContracts = [];
         state.hideLowHolderTokens = true;
     });
 
+    afterAll(() => {
+        state.networkId = "mainnet";
+    });
+
+    // A token reporting USDC's symbol from another contract.
+    function otherUsdc() {
+        return {
+            address: FAKE_ETH_CONTRACT,
+            symbol: "USDC",
+            decimals: 6,
+            balance: "12.5",
+            holders: 900000,
+        };
+    }
+
+    test("a bundled symbol from another contract is not selectable", () => {
+        render([otherUsdc()]);
+        expect(select.children).toEqual([]);
+    });
+
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+    // mainnet contracts, so on Sepolia any contract may carry its symbols.
+    test("with Sepolia active, a bundled symbol from another contract is selectable", () => {
+        state.networkId = "sepolia";
+        render([otherUsdc()]);
+        expect(select.children).toHaveLength(1);
+        expect(select.children[0].value).toBe(FAKE_ETH_CONTRACT);
+    });
+
     test("a fake ETH token is not selectable", () => {
         render([
             {
@@ -627,7 +687,12 @@ describe("surface 3: the balance list", () => {
                 decimals: "6",
             }),
         ]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        const balances = await fetchTokenBalances(
+            HOLDER,
+            BLOCKSCOUT,
+            [],
+            MAINNET,
+        );
         expect(balances).toHaveLength(1);
         expect(balances[0].symbol).toBe(" USDC ");
     });
@@ -641,11 +706,40 @@ describe("surface 3: the balance list", () => {
                 decimals: "6",
             }),
         ]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        const balances = await fetchTokenBalances(
+            HOLDER,
+            BLOCKSCOUT,
+            [],
+            MAINNET,
+        );
         expect(balances).toHaveLength(1);
         expect(balances[0].symbol).toBe("USDC");
     });
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+    // mainnet contracts, so on Sepolia any contract may carry its symbols.
+    test("a bundled symbol from another contract is listed on Sepolia only", async () => {
+        respondWith([fakeEthItem({ symbol: "USDC", decimals: "6" })]);
+        expect(
+            await fetchTokenBalances(HOLDER, BLOCKSCOUT, [], MAINNET),
+        ).toEqual([]);
+        const sepolia = await fetchTokenBalances(
+            HOLDER,
+            BLOCKSCOUT,
+            [],
+            SEPOLIA,
+        );
+        expect(sepolia).toHaveLength(1);
+        expect(sepolia[0].symbol).toBe("USDC");
+    });
+
+    test("a fake ETH token is filtered on Sepolia too", async () => {
+        respondWith([fakeEthItem()]);
+        expect(
+            await fetchTokenBalances(HOLDER, BLOCKSCOUT, [], SEPOLIA),
+        ).toEqual([]);
+    });
+
     // The trap in this change: the user's real ETH balance is not an ERC-20
     // and is fetched over RPC in refreshBalances, so it never passes through
     // this loop at all.  An explorer row that is not an ERC-20 is dropped
diff --git a/tests/trackedTokenBalances.test.js b/tests/trackedTokenBalances.test.js
index d00291f..0ab03c9 100644
--- a/tests/trackedTokenBalances.test.js
+++ b/tests/trackedTokenBalances.test.js
@@ -133,13 +133,13 @@ function trackedRow(balance, decimals = null, holders = null) {
     };
 }
 
-async function refresh(addresses, trackedTokens) {
+async function refresh(addresses, trackedTokens, networkId = "mainnet") {
     await refreshBalances(
         [{ addresses }],
         RPC_URL,
         EXPLORER_URL,
         trackedTokens,
-        "mainnet",
+        networkId,
         new AbortController().signal,
     );
     return addresses;
@@ -307,3 +307,76 @@ test("a tracked token wearing a known symbol from another contract is not listed
     );
     expect(first.tokenBalances).toEqual([]);
 });
+
+// https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+// Ethereum Mainnet contracts. A token outside the tracked tokens with an
+// unknown holder count is listed only when the bundled list names it.
+test("an untracked bundled token with an unknown holder count is listed on Ethereum Mainnet only", async () => {
+    explorerRows = [explorerRow(USDC, "USDC", 5000000, null)];
+    const [mainnet] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [],
+    );
+    expect(mainnet.tokenBalances).toEqual([
+        {
+            address: USDC,
+            name: "USDC",
+            symbol: "USDC",
+            decimals: 6,
+            balance: "5.0",
+            holders: null,
+        },
+    ]);
+    const [sepolia] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [],
+        "sepolia",
+    );
+    expect(sepolia.tokenBalances).toEqual([]);
+});
+
+test("a tracked token at a bundled token's address takes the bundled scale on Ethereum Mainnet only", async () => {
+    holdings[USDC] = { [FIRST]: 5000000n };
+    // The tracked entry records no decimals, and Blockscout fails.
+    const tracked = [
+        { address: USDC, symbol: "USDC", name: "USD Coin", decimals: null },
+    ];
+    const row = (balance) => ({
+        address: USDC,
+        name: "USD Coin",
+        symbol: "USDC",
+        decimals: null,
+        balance: balance,
+        holders: null,
+    });
+    const [mainnet] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        tracked,
+    );
+    expect(mainnet.tokenBalances).toEqual([row("5.0")]);
+    const [sepolia] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        tracked,
+        "sepolia",
+    );
+    expect(sepolia.tokenBalances).toEqual([row(null)]);
+});
+
+test("with Sepolia active, a tracked token wearing a bundled symbol from another contract is listed", async () => {
+    holdings[OTHER] = { [FIRST]: 5000000n };
+    const [first] = await refresh(
+        [{ address: FIRST, tokenBalances: [] }],
+        [{ address: OTHER, symbol: "USDC", name: "Other", decimals: 6 }],
+        "sepolia",
+    );
+    expect(first.tokenBalances).toEqual([
+        {
+            address: OTHER,
+            name: "Other",
+            symbol: "USDC",
+            decimals: null,
+            balance: "5.0",
+            holders: null,
+        },
+    ]);
+});
diff --git a/tests/transactions.test.js b/tests/transactions.test.js
index 73d0b64..0ce34d4 100644
--- a/tests/transactions.test.js
+++ b/tests/transactions.test.js
@@ -144,6 +144,7 @@ function tokenTx(overrides = {}) {
         isError: false,
         contractAddress: USDC_CONTRACT,
         holders: 3500000,
+        chainId: "0x1",
         ...overrides,
     };
 }
@@ -259,6 +260,32 @@ describe("known-symbol spoof verification", () => {
         expect(result.newFraudContracts).toEqual([NOVEL_SPAM_CONTRACT]);
     });
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled list holds
+    // mainnet contracts, so its symbols are not known symbols on Sepolia.
+    test("on Sepolia, a bundled symbol from another contract is kept", () => {
+        const sepoliaToken = tokenTx({
+            symbol: "USDC",
+            contractAddress: NOVEL_SPAM_CONTRACT,
+            holders: 5000000,
+            chainId: "0xaa36a7",
+        });
+        const result = filterTransactions([sepoliaToken], filters());
+        expect(result.transactions).toEqual([sepoliaToken]);
+        expect(result.newFraudContracts).toEqual([]);
+    });
+
+    test('on Sepolia, "ETH" as an ERC-20 is still spoofed', () => {
+        const fakeEth = tokenTx({
+            symbol: "ETH",
+            contractAddress: NOVEL_SPAM_CONTRACT,
+            holders: 5000000,
+            chainId: "0xaa36a7",
+        });
+        expect(filterTransactions([fakeEth], filters()).transactions).toEqual(
+            [],
+        );
+    });
+
     test("the genuine contract for that symbol is not spoofed", () => {
         const genuine = tokenTx();
         const result = filterTransactions([genuine], filters());
@@ -1495,6 +1522,41 @@ describe("fetchRecentTransactions merge and dedup", () => {
         expect(mainnet[0].chainId).toBe("0x1");
     });
 
+    // https://git.eeqj.de/sneak/AutistMask/issues/632: the bundled token list
+    // names a contract only on Ethereum Mainnet. On Sepolia, a call to the
+    // contract at USDC's mainnet address is labelled with the network's native
+    // currency. A call to any contract the wallet does not name gets that label.
+    test("a contract call on Sepolia is not named by the bundled list", async () => {
+        respondWith(
+            [
+                {
+                    hash: "0x" + "b".repeat(64),
+                    block_number: 21000095,
+                    timestamp: TS,
+                    from: { hash: VICTIM },
+                    to: { hash: USDC_CONTRACT, is_contract: true },
+                    value: "0",
+                    method: "approve",
+                    status: "ok",
+                },
+            ],
+            [],
+        );
+        const sepolia = await fetchRecentTransactions(
+            VICTIM,
+            BLOCKSCOUT,
+            "0xaa36a7",
+        );
+        expect(sepolia[0].directionLabel).toBe("Approve");
+        expect(sepolia[0].symbol).toBe("SepoliaETH");
+        const mainnet = await fetchRecentTransactions(
+            VICTIM,
+            BLOCKSCOUT,
+            "0x1",
+        );
+        expect(mainnet[0].symbol).toBe("USDC");
+    });
+
     test("the fake token transfer survives fetching and is then filtered", async () => {
         respondWith(
             [],
diff --git a/tests/unknownScaleSend.test.js b/tests/unknownScaleSend.test.js
index d386604..104ac46 100644
--- a/tests/unknownScaleSend.test.js
+++ b/tests/unknownScaleSend.test.js
@@ -167,7 +167,8 @@ function row(token = {}, value = FIVE_WETH) {
 }
 
 // Fetch the explorer's rows through the real fetcher and put them exactly where
-// refreshBalances() puts them. The node reports the holding the explorer does.
+// refreshBalances() puts them on Ethereum Mainnet. The node reports the holding
+// the explorer does.
 async function fetchOnto(items) {
     mockProvider.tokenUnits = BigInt(items[0].value);
     debugFetch.mockImplementation(async () => ({
@@ -176,7 +177,7 @@ async function fetchOnto(items) {
         statusText: "OK",
         json: async () => items,
     }));
-    const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+    const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, [], "0x1");
     state.wallets = [
         {
             name: "Wallet 1",