diff --git a/src/agents/pi-tools.abort.ts b/src/agents/pi-tools.abort.ts
index a14629782c..e12b38da48 100644
--- a/src/agents/pi-tools.abort.ts
+++ b/src/agents/pi-tools.abort.ts
@@ -22,9 +22,14 @@ function combineAbortSignals(a?: AbortSignal, b?: AbortSignal): AbortSignal | un
   if (b?.aborted) {
     return b;
   }
-  if (typeof AbortSignal.any === "function") {
-    return AbortSignal.any([a as AbortSignal, b as AbortSignal]);
+  if (
+    typeof AbortSignal.any === "function" &&
+    a instanceof AbortSignal &&
+    b instanceof AbortSignal
+  ) {
+    return AbortSignal.any([a, b]);
   }
+
   const controller = new AbortController();
   const onAbort = () => controller.abort();
   a?.addEventListener("abort", onAbort, { once: true });