diff --git a/client/sub_client.c b/client/sub_client.c
index caad3f6f..ad0b3ee9 100644
--- a/client/sub_client.c
+++ b/client/sub_client.c
@@ -51,7 +51,7 @@ static HANDLE timeout_h = NULL;
 #endif
 
 #ifdef WIN32
-void timeout_cb(PVOID lpParameter, BOOLEAN TimerOrWaitFired)
+void CALLBACK timeout_cb(PVOID lpParameter, BOOLEAN TimerOrWaitFired)
 {
 	UNUSED(lpParameter);
 	UNUSED(TimerOrWaitFired);