diff --git a/parson.c b/parson.c
index e485039..943b898 100644
--- a/parson.c
+++ b/parson.c
@@ -23,6 +23,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
+#include <stddef.h>
 #include "parson.h"
 
 #define STARTING_CAPACITY 10