diff --git a/lib/rb/ext/struct.c b/lib/rb/ext/struct.c
index 4947e26..8dd5c3e 100644
--- a/lib/rb/ext/struct.c
+++ b/lib/rb/ext/struct.c
@@ -19,6 +19,7 @@
 
 #include <struct.h>
 #include <constants.h>
+#include "macros.h"
 
 #ifndef HAVE_STRLCPY