diff --git a/src/hb-config.hh b/src/hb-config.hh
index 67e8fe8..a5243d1 100644
--- a/src/hb-config.hh
+++ b/src/hb-config.hh
@@ -35,6 +35,10 @@
 #include "config.h"
 #endif
 
+#ifndef HB_EXPERIMENTAL
+#define HB_NO_BEYOND_64K
+#endif
+
 #ifndef HB_BORING_EXPANSION
 #define HB_NO_BORING_EXPANSION
 #endif