diff --git a/src/test/test-date.c b/src/test/test-date.c
index 2b96983e2c..c7d239e22f 100644
--- a/src/test/test-date.c
+++ b/src/test/test-date.c
@@ -1,5 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include <unistd.h>
+
 #include "alloc-util.h"
 #include "string-util.h"
 #include "tests.h"