diff --git a/grep.c b/grep.c
index 1b89242..d74f2fc 100644
--- a/grep.c
+++ b/grep.c
@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <unistd.h>
 
 #include "queue.h"