diff --git a/runtime/bin/file_system_watcher_macos.cc b/runtime/bin/file_system_watcher_macos.cc
index 6d51e9114ba..1ae1810f65d 100644
--- a/runtime/bin/file_system_watcher_macos.cc
+++ b/runtime/bin/file_system_watcher_macos.cc
@@ -136,7 +136,9 @@ class FSEventsWatcher {
     if (watcher == NULL) {
       watcher_monitor->Enter();
       watcher = new FSEventsWatcher();
-      watcher_monitor->Wait(Monitor::kNoTimeout);
+      while (watcher->run_loop_ == NULL) {
+        watcher_monitor->Wait(Monitor::kNoTimeout);
+      }
       watcher_monitor->Exit();
     }
     watcher->users_++;