Move HB_EXTERN
diff --git a/src/hb-common.h b/src/hb-common.h
index 2532d69..ae23698 100644
--- a/src/hb-common.h
+++ b/src/hb-common.h
@@ -33,6 +33,10 @@
#ifndef HB_COMMON_H
#define HB_COMMON_H
+#ifndef HB_EXTERN
+#define HB_EXTERN extern
+#endif
+
#ifndef HB_BEGIN_DECLS
# ifdef __cplusplus
# define HB_BEGIN_DECLS extern "C" {
diff --git a/src/hb.h b/src/hb.h
index fc75a69..c5e7072 100644
--- a/src/hb.h
+++ b/src/hb.h
@@ -28,10 +28,6 @@
#define HB_H
#define HB_H_IN
-#ifndef HB_EXTERN
-#define HB_EXTERN extern
-#endif
-
#include "hb-blob.h"
#include "hb-buffer.h"
#include "hb-common.h"