diff --git a/test_ffi/tests/integration_tests.rs b/test_ffi/tests/integration_tests.rs
index e850a174a3..a4f233e45d 100644
--- a/test_ffi/tests/integration_tests.rs
+++ b/test_ffi/tests/integration_tests.rs
@@ -176,8 +176,10 @@ fn thread_safe_callback() {
   let expected = "\
     Callback on main thread\n\
     Callback on worker thread\n\
+    STORED_FUNCTION cleared\n\
     Calling callback, isolate should stay asleep until callback is called\n\
     Callback being called\n\
+    STORED_FUNCTION cleared\n\
     Isolate should now exit\n";
   assert_eq!(stdout, expected);
   assert_eq!(stderr, "");
diff --git a/test_ffi/tests/thread_safe_test.js b/test_ffi/tests/thread_safe_test.js
index 62c78279dd..41ab803be8 100644
--- a/test_ffi/tests/thread_safe_test.js
+++ b/test_ffi/tests/thread_safe_test.js
@@ -71,6 +71,8 @@ dylib.symbols.call_stored_function();
 
 // Unref both main and worker thread callbacks and terminate the worker: Note, the stored function pointer in lib is now dangling.
 
+dylib.symbols.store_function(null);
+
 mainThreadCallback.unref();
 await sendWorkerMessage("unref");
 worker.terminate();
@@ -90,6 +92,9 @@ cleanupCallback.ref();
 
 function cleanup() {
   cleanupCallback.unref();
+  dylib.symbols.store_function(null);
+  mainThreadCallback.close();
+  cleanupCallback.close();
   console.log("Isolate should now exit");
 }
 
diff --git a/test_ffi/tests/thread_safe_test_worker.js b/test_ffi/tests/thread_safe_test_worker.js
index a87a975569..fb3365bf81 100644
--- a/test_ffi/tests/thread_safe_test_worker.js
+++ b/test_ffi/tests/thread_safe_test_worker.js
@@ -35,7 +35,7 @@ self.addEventListener("message", ({ data }) => {
   } else if (data === "call") {
     dylib.symbols.call_stored_function();
   } else if (data === "unref") {
-    callback.unref();
+    callback.close();
   }
   self.postMessage("done");
 });