diff --git a/extensions/signal/src/monitor/quote-context.ts b/extensions/signal/src/monitor/quote-context.ts
index e0d8fb89324..5c1b031da43 100644
--- a/extensions/signal/src/monitor/quote-context.ts
+++ b/extensions/signal/src/monitor/quote-context.ts
@@ -64,6 +64,11 @@ export function normalizeSignalQuoteId(rawId?: SignalQuote["id"]) {
   if (!trimmed) {
     return undefined;
   }
+  // Only accept decimal digit strings — reject hex (0x10), scientific (1e3),
+  // and other Number()-parseable formats that would normalize to a different ID.
+  if (!/^\d+$/.test(trimmed)) {
+    return undefined;
+  }
   const numeric = Number(trimmed);
   return Number.isInteger(numeric) && numeric > 0 ? String(numeric) : undefined;
 }