diff --git a/src/shared/tests.h b/src/shared/tests.h
index 33304903ba..5c933c4801 100644
--- a/src/shared/tests.h
+++ b/src/shared/tests.h
@@ -1,6 +1,8 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 #pragma once
 
+#include <unistd.h>
+
 #include "errno-list.h"
 #include "errno-util.h"
 #include "forward.h"