diff --git a/core/include/ten_runtime/test/env_tester.h b/core/include/ten_runtime/test/env_tester.h
index 0be0a0623..1fa9d31fd 100644
--- a/core/include/ten_runtime/test/env_tester.h
+++ b/core/include/ten_runtime/test/env_tester.h
@@ -17,7 +17,7 @@ TEN_RUNTIME_API bool ten_env_tester_on_start_done(ten_env_tester_t *self,
                                                   ten_error_t *err);
 
 TEN_RUNTIME_API bool ten_env_tester_on_stop_done(ten_env_tester_t *self,
-                                                  ten_error_t *err);
+                                                 ten_error_t *err);
 
 typedef void (*ten_env_tester_cmd_result_handler_func_t)(
     ten_env_tester_t *self, ten_shared_ptr_t *cmd_result, void *user_data,
diff --git a/core/include/ten_runtime/test/extension_tester.h b/core/include/ten_runtime/test/extension_tester.h
index 35ae47124..67023e3ee 100644
--- a/core/include/ten_runtime/test/extension_tester.h
+++ b/core/include/ten_runtime/test/extension_tester.h
@@ -22,6 +22,7 @@ typedef enum TEN_EXTENSION_TESTER_TEST_MODE {
 
 typedef void (*ten_extension_tester_on_start_func_t)(
     ten_extension_tester_t *self, ten_env_tester_t *ten_env);
+
 typedef void (*ten_extension_tester_on_stop_func_t)(
     ten_extension_tester_t *self, ten_env_tester_t *ten_env);
 
diff --git a/core/src/ten_runtime/test/test_extension.c b/core/src/ten_runtime/test/test_extension.c
index ba2201dee..045c64761 100644
--- a/core/src/ten_runtime/test/test_extension.c
+++ b/core/src/ten_runtime/test/test_extension.c
@@ -100,9 +100,10 @@ static void test_extension_on_stop(ten_extension_t *self, ten_env_t *ten_env) {
       test_extension_get_extension_tester_ptr(ten_env);
   self->user_data = tester;
 
-  ten_runloop_post_task_tail(tester->tester_runloop,
-                             ten_extension_tester_on_test_extension_stop_task,
-                             tester, NULL);
+  int rc = ten_runloop_post_task_tail(
+      tester->tester_runloop, ten_extension_tester_on_test_extension_stop_task,
+      tester, NULL);
+  TEN_ASSERT(!rc, "Should not happen.");
 }
 
 void ten_builtin_test_extension_ten_env_notify_on_start_done(