diff --git a/src/sem/ntapi_sem_ioctl.c b/src/sem/ntapi_sem_ioctl.c
index 63f0eec..ddac294 100644
--- a/src/sem/ntapi_sem_ioctl.c
+++ b/src/sem/ntapi_sem_ioctl.c
@@ -90,10 +90,10 @@ int32_t	__stdcall __ntapi_sem_ioctl(
 	/* lock */
 	hlock = &(__ntapi_internals()->hlock);
 
-	if (at_locked_cas(hlock,0,1))
-		return __sem_ioctl_return(
-			mapaddr,0,
-			NT_STATUS_RESOURCE_NOT_OWNED);
+	while (at_locked_cas(hlock,0,1))
+		__ntapi->zw_delay_execution(
+			NT_SYNC_NON_ALERTABLE,
+			&(nt_timeout){{0,0}});
 
 	/* semop array to section */
 	__ntapi->tt_generic_memcpy(