diff --git a/images.h b/images.h
index 03390c8..0a80d4e 100644
--- a/images.h
+++ b/images.h
@@ -1,5 +1,6 @@
 #ifndef IMAGES_H
 #define IMAGES_H "v0.1.1"
+#include <stddef.h>
 
 typedef struct _color {
     unsigned char  r;