diff --git a/cthreads.c b/cthreads.c
index dea3270..821f642 100644
--- a/cthreads.c
+++ b/cthreads.c
@@ -70,7 +70,7 @@ int cthreads_thread_detach(struct cthreads_thread thread) {
   #endif
 
   #ifdef _WIN32
-    return CloseHandle(thread.wThread);
+    return CloseHandle(thread.wThread)==0;
   #else
     return pthread_detach(thread.pThread);
   #endif