diff --git a/src/shared/chainSwitch.js b/src/shared/chainSwitch.js
index 5c86f84..3bab5b9 100644
--- a/src/shared/chainSwitch.js
+++ b/src/shared/chainSwitch.js
@@ -47,12 +47,20 @@ function clearPopupCaches() {
 // lock, so it is never switched while a follow of a switch saved elsewhere
 // waits for the lock (followStoredSettings() in src/popup/index.js): that
 // follow runs first, and this switch is made after it.
+//
+// The switch is also applied to the stored record that the save has just read,
+// as the background applies its own switch. A save writes only the fields that
+// this page changed since its last save. A cleared balance of "0" is no change
+// when this page last saved "0" too. The balance that the background stored
+// since then would otherwise stay under the new network
+// (https://git.eeqj.de/sneak/AutistMask/issues/653).
 async function onChainSwitch(newNetworkId) {
     const { state, saveState } = require("./state");
     let net = null;
-    await saveState(() => {
+    await saveState((stored) => {
         if (state.networkId === newNetworkId) return false;
         net = applyChainSwitchFields(state, newNetworkId);
+        applyChainSwitchFields(stored, newNetworkId);
         clearPopupCaches();
     });
     return net;
diff --git a/src/shared/chainSwitchFields.js b/src/shared/chainSwitchFields.js
index cea6ef2..b6e327a 100644
--- a/src/shared/chainSwitchFields.js
+++ b/src/shared/chainSwitchFields.js
@@ -4,8 +4,9 @@
 // Split out of chainSwitch.js so the background can perform a chain switch
 // without the singleton being reachable from its bundle at all. The popup
 // still goes through onChainSwitch() (chainSwitch.js), which applies this to
-// the singleton and saves; the background applies it to the detached record of
-// its own read-modify-write (src/background/state.js).
+// the singleton and to the stored record that its save reads; the background
+// applies it to the detached record of its own read-modify-write
+// (src/background/state.js).
 //
 // Everything here is synchronous and touches nothing but the objects it is
 // given: no storage, no caches, no imports beyond the network table. That is
diff --git a/src/shared/state.js b/src/shared/state.js
index 227763c..1d75e94 100644
--- a/src/shared/state.js
+++ b/src/shared/state.js
@@ -591,8 +591,10 @@ function reportSaveFailure(err) {
 //
 // `beforeWrite`, when given, is called inside the lock with the stored record
 // as just read, before this page's state is compared against it. It may change
-// `state`, and this save writes that change. When it returns false, nothing is
-// written; any other return lets the save go ahead.
+// `state`, and this save writes that change. It may also change the stored
+// record: a field that this page did not change is written as `beforeWrite`
+// left it. When it returns false, nothing is written; any other return lets the
+// save go ahead.
 function saveState(beforeWrite) {
     const turn = withLock("autistmask", () => saveStateOnce(beforeWrite));
     // Every failed save is reported, whether or not the caller awaited this
diff --git a/tests/balanceRefreshNetworkSwitch.test.js b/tests/balanceRefreshNetworkSwitch.test.js
index 94b0a4a..22cc4fe 100644
--- a/tests/balanceRefreshNetworkSwitch.test.js
+++ b/tests/balanceRefreshNetworkSwitch.test.js
@@ -6,6 +6,9 @@
 // approved a site's request, which changes only the stored record. Driven
 // through the real popup over a stored profile on Ethereum Mainnet. The same
 // refresh in the background is in tests/backgroundStateIsolation.test.js.
+//
+// The last test covers a refresh by the background that is saved just before
+// the switch in Settings (https://git.eeqj.de/sneak/AutistMask/issues/653).
 
 const {
     bootPopup,
@@ -159,3 +162,49 @@ test("a refresh that returns after the background switched the network writes no
 
     expectNothingStored(page);
 });
+
+// The background's refresh saves Ethereum Mainnet's balances while the switch
+// in Settings waits for the lock. This page last saved a balance of "0" and no
+// tokens, the same values the switch sets.
+test("a background refresh saved while a switch in Settings waits for the lock leaves none of its balances stored", async () => {
+    const profile = unversionedValidProfile();
+    profile.wallets[0].addresses[0].balance = "0";
+    const page = await bootPopup(profile);
+    expect(page.pageErrors).toEqual([]);
+    const background = require("../src/background/state");
+    await page.click("btn-settings");
+
+    // The background takes the lock first. Once let go, the background saves
+    // balances as backgroundRefresh() in src/background/index.js does.
+    let letGo;
+    const refreshSave = background.updateState(async (fresh) => {
+        await new Promise((resolve) => {
+            letGo = resolve;
+        });
+        fresh.wallets[0].addresses[0].balance = "7.0";
+        fresh.wallets[0].addresses[0].tokenBalances = [
+            {
+                address: TOKEN_ADDRESS,
+                name: "Test Token",
+                symbol: "TST",
+                decimals: 18,
+                balance: "5.0",
+                holders: null,
+            },
+        ];
+        fresh.lastBalanceRefresh = Date.now();
+    });
+    await page.settle();
+
+    const select = page.node("settings-network");
+    select.value = "sepolia";
+    const switching = Promise.all(select.listeners.change.map((fn) => fn()));
+    await page.settle();
+
+    letGo();
+    await refreshSave;
+    await switching;
+    await page.settle();
+
+    expectNothingStored(page);
+});