diff --git a/src/include/field.h b/src/include/field.h
index c4d2424..5cfe349 100644
--- a/src/include/field.h
+++ b/src/include/field.h
@@ -1,6 +1,8 @@
 #ifndef FIELD_H
 #define FIELD_H
 
+#include <stddef.h>
+
 #include "apple.h"
 
 typedef struct field_T {