diff --git a/http_parser.h b/http_parser.h
index 9b699dc..b0250fe 100644
--- a/http_parser.h
+++ b/http_parser.h
@@ -28,6 +28,9 @@
 extern "C" {
 #endif 
 
+#ifdef _MSC_VER
+	#include <stddef.h>
+#endif
 #include <sys/types.h> 
 
 typedef struct http_parser http_parser;