diff --git a/lib/libc/strnlen.c b/lib/libc/strnlen.c
index fca7ad2..b944e95 100644
--- a/lib/libc/strnlen.c
+++ b/lib/libc/strnlen.c
@@ -26,8 +26,10 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
+/*
+ * Portions copyright (c) 2018, ARM Limited and Contributors.
+ * All rights reserved.
+ */
 
 #include <string.h>