diff --git a/ctrtool/utils.c b/ctrtool/utils.c
index cfaf184..1f21f07 100644
--- a/ctrtool/utils.c
+++ b/ctrtool/utils.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <string.h>
 #include <sys/stat.h>
 #ifdef _WIN32
 #include <direct.h>