diff --git a/src/nxt_router.c b/src/nxt_router.c
index e5355612..39cfd3bc 100644
--- a/src/nxt_router.c
+++ b/src/nxt_router.c
@@ -2655,6 +2655,9 @@ nxt_router_response_ready_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg,
     }
 
     ar = rc->ap;
+    if (nxt_slow_path(ar == NULL)) {
+        return;
+    }
 
     if (msg->port_msg.last != 0) {
         nxt_debug(task, "router data create last buf");