diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index 0b4041a..fd03e91 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -178,14 +178,14 @@
 #endif
 				 );
 
-	if (success >= 0) {
+	if (success == 0) {
 #if defined(PY_PTHREAD_D4) || defined(PY_PTHREAD_D6) || defined(PY_PTHREAD_D7)
 		pthread_detach(&th);
 #elif defined(PY_PTHREAD_STD)
 		pthread_detach(th);
 #endif
 	}
-	return success < 0 ? 0 : 1;
+	return success != 0 ? 0 : 1;
 }
 
 long PyThread_get_thread_ident _P0()