diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index 2b92e7d1fd40..3fe58d9f38ea 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -615,7 +615,9 @@ JS_ShutDown(void)
     }
 #endif
 
+#ifdef JS_THREADSAFE
     WorkerThreadState().finish();
+#endif
 
     PRMJ_NowShutdown();