diff --git a/src/util/list_ref.h b/src/util/list_ref.h
index 0826d8938f..7a9c5a2ec1 100644
--- a/src/util/list_ref.h
+++ b/src/util/list_ref.h
@@ -5,6 +5,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
+#include "util/buffer.h"
 #include "util/object_ref.h"
 
 namespace lean {