diff --git a/library/md2.c b/library/md2.c
index 180a25b..43c129f 100644
--- a/library/md2.c
+++ b/library/md2.c
@@ -36,6 +36,8 @@
 
 #include "polarssl/md2.h"
 
+#include <string.h>
+
 #if defined(POLARSSL_FS_IO)
 #include <stdio.h>
 #endif