diff --git a/strings.c b/strings.c
index c380752..27cecc5 100644
--- a/strings.c
+++ b/strings.c
@@ -1,5 +1,6 @@
 /* See LICENSE file for copyright and license details. */
 #include <ctype.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>