diff --git a/internal/ircserver/commands.go b/internal/ircserver/commands.go
index 2a8b75a..c2b4e16 100644
--- a/internal/ircserver/commands.go
+++ b/internal/ircserver/commands.go
@@ -1227,9 +1227,12 @@ func (c *Conn) handlePassPostReg(
 		return
 	}
 
+	// The IRC listener cannot add a connection to an existing
+	// session; only the HTTP API login can.
 	c.sendFromServer("NOTICE", c.currentNick(),
-		"Password set. You can reconnect using "+
-			"PASS <password> with your nick.",
+		"Password set. Another client can log in to this "+
+			"session over the HTTP API: POST /api/v1/login "+
+			"with your nick and this password.",
 	)
 }
 
diff --git a/internal/ircserver/server_test.go b/internal/ircserver/server_test.go
index 7c397f7..bff359c 100644
--- a/internal/ircserver/server_test.go
+++ b/internal/ircserver/server_test.go
@@ -1250,6 +1250,9 @@ func TestAwaySetAndClear(t *testing.T) {
 	assertContains(t, clearLines, " 305 ", "RPL_UNAWAY")
 }
 
+// TestHandlePassPostRegistration checks the NOTICE that
+// confirms PASS after registration. It points to the HTTP API
+// login, the only way to add a client to an existing session.
 func TestHandlePassPostRegistration(t *testing.T) {
 	t.Parallel()
 
@@ -1262,7 +1265,11 @@ func TestHandlePassPostRegistration(t *testing.T) {
 	)
 
 	assertContains(
-		t, lines, "Password set", "password confirmation",
+		t, lines,
+		" NOTICE passuser :Password set. Another client can log "+
+			"in to this session over the HTTP API: "+
+			"POST /api/v1/login with your nick and this password.",
+		"password confirmation",
 	)
 }