diff --git a/lib/libstdthreads/thrd.c b/lib/libstdthreads/thrd.c
index f0ce55a567c4..b0e36ef618fb 100644
--- a/lib/libstdthreads/thrd.c
+++ b/lib/libstdthreads/thrd.c
@@ -108,7 +108,8 @@ thrd_join(thrd_t thr, int *res)
 
 	if (pthread_join(thr, &value_ptr) != 0)
 		return (thrd_error);
-	*res = (intptr_t)value_ptr;
+	if (res != NULL)
+		*res = (intptr_t)value_ptr;
 	return (thrd_success);
 }