diff --git a/sleep.c b/sleep.c
index c5e9e49..4c53e44 100644
--- a/sleep.c
+++ b/sleep.c
@@ -1,4 +1,5 @@
 /* See LICENSE file for copyright and license details. */
+#include <limits.h>
 #include <stdlib.h>
 #include <unistd.h>