diff --git a/extensions/browser/src/browser/pw-session.get-page-for-targetid.extension-fallback.test.ts b/extensions/browser/src/browser/pw-session.get-page-for-targetid.extension-fallback.test.ts
index 9309f78645c..204ae142483 100644
--- a/extensions/browser/src/browser/pw-session.get-page-for-targetid.extension-fallback.test.ts
+++ b/extensions/browser/src/browser/pw-session.get-page-for-targetid.extension-fallback.test.ts
@@ -147,7 +147,9 @@ describe("pw-session getPageForTargetId", () => {
       expect(fetchInit?.headers).toEqual({});
       expect(fetchInit?.redirect).toBe("manual");
       expect(fetchInit?.signal).toBeInstanceOf(AbortSignal);
-      expect(fetchInit?.dispatcher).toBeDefined();
+      if (fetchInit?.dispatcher === undefined) {
+        throw new Error("expected extension fallback fetch dispatcher");
+      }
     } finally {
       fetchSpy.mockRestore();
     }
diff --git a/extensions/browser/src/browser/server-context.remote-profile-tab-ops.fallback.test.ts b/extensions/browser/src/browser/server-context.remote-profile-tab-ops.fallback.test.ts
index 1263d462ae0..27595188766 100644
--- a/extensions/browser/src/browser/server-context.remote-profile-tab-ops.fallback.test.ts
+++ b/extensions/browser/src/browser/server-context.remote-profile-tab-ops.fallback.test.ts
@@ -309,6 +309,8 @@ describe("browser remote profile fallback and attachOnly behavior", () => {
     expect(fetchInit.headers).toEqual({});
     expect(fetchInit.redirect).toBe("manual");
     expect(fetchInit.signal).toBeInstanceOf(AbortSignal);
-    expect(fetchInit.dispatcher).toBeDefined();
+    if (fetchInit.dispatcher === undefined) {
+      throw new Error("expected remote browser fetch dispatcher");
+    }
   });
 });