diff --git a/packages/connect-web/browserstack/karma-fixup-AbortController.js b/packages/connect-web/browserstack/karma-fixup-AbortController.js
index 85df94429..d674ead3b 100644
--- a/packages/connect-web/browserstack/karma-fixup-AbortController.js
+++ b/packages/connect-web/browserstack/karma-fixup-AbortController.js
@@ -15,7 +15,7 @@
 // a simplistic polyfill for AbortController and AbortSignal
 
 (function () {
-  if (!globalThis.AbortController || !globalThis.AbortSignal) {
+  if (globalThis.AbortController && globalThis.AbortSignal) {
     // `throwIfAborted` was added much later.
     if (!globalThis.AbortSignal.prototype.throwIfAborted) {
       globalThis.AbortSignal.prototype.throwIfAborted = function () {