diff --git a/Source/win32/GSRunLoopCtxt.m b/Source/win32/GSRunLoopCtxt.m
index 9955d1320..861a1a6cc 100644
--- a/Source/win32/GSRunLoopCtxt.m
+++ b/Source/win32/GSRunLoopCtxt.m
@@ -526,6 +526,7 @@ static const NSMapTableValueCallBacks WatcherMapValueCallBacks =
 
   if (handle == threadInfo->event)
     {
+      watcher = nil;
       [threadInfo fire];
     }
   else