diff --git a/lang/c++/api/Zigzag.hh b/lang/c++/api/Zigzag.hh

index bf831d24..7ce5c2cf 100644

--- a/lang/c++/api/Zigzag.hh

+++ b/lang/c++/api/Zigzag.hh

@@ -20,6 +20,7 @@

 #define avro_Encoding_hh__

 #include <stdint.h>

+#include <stddef.h>

 #include <array>

 #include "Config.hh"