diff --git a/test/repositories/UnoptimizedInMemoryRepositoryTests.test.ts b/test/repositories/UnoptimizedInMemoryRepositoryTests.test.ts
index dc22f15..35956b3 100644
--- a/test/repositories/UnoptimizedInMemoryRepositoryTests.test.ts
+++ b/test/repositories/UnoptimizedInMemoryRepositoryTests.test.ts
@@ -257,6 +257,17 @@ describe("UnoptimizedInMemoryRepository", () => {
       expect(mockCallback).toHaveBeenCalledWith(mockEtas[0]); // First notification
       expect(mockCallback).not.toHaveBeenCalledWith(mockEtas[mockEtas.length - 1]); // Last notification
     });
+
+    test("does nothing if the listener doesn't exist", async () => {
+      const mockCallback = jest.fn();
+      repository.subscribeToEtaUpdates(mockCallback);
+
+      const mockEtas = generateMockEtas();
+
+      repository.unsubscribeFromEtaUpdates(() => {});
+      await repository.addOrUpdateEta(mockEtas[0]);
+      expect(mockCallback).toHaveBeenCalledTimes(1);
+    });
   });
 
   describe("getOrderedStopByRouteAndStopId", () => {