diff --git a/async.c b/async.c
index d955203..ac343b5 100644
--- a/async.c
+++ b/async.c
@@ -336,7 +336,8 @@ static void __redisAsyncDisconnect(redisAsyncContext *ac) {
 
     if (ac->err == 0) {
         /* For clean disconnects, there should be no pending callbacks. */
-        assert(__redisShiftCallback(&ac->replies,NULL) == REDIS_ERR);
+        int ret = __redisShiftCallback(&ac->replies,NULL);
+        assert(ret == REDIS_ERR);
     } else {
         /* Disconnection is caused by an error, make sure that pending
          * callbacks cannot call new commands. */