diff --git a/include/os.h b/include/os.h
index 566514d4a..d587f3441 100644
--- a/include/os.h
+++ b/include/os.h
@@ -51,6 +51,7 @@ SOFTWARE.
 
 #include "misc.h"
 #include <stdarg.h>
+#include <string.h>
 
 #define SCREEN_SAVER_ON   0
 #define SCREEN_SAVER_OFF  1