diff --git a/src/backend/backend.c b/src/backend/backend.c
index 9893b84..ae8ea6d 100644
--- a/src/backend/backend.c
+++ b/src/backend/backend.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: MPL-2.0
 // Copyright (c) Yuxuan Shui <yshuiv7@gmail.com>
+#include <xcb/sync.h>
 #include <xcb/xcb.h>
 
 #include "backend/backend.h"