diff --git a/src/hb-buffer-private.hh b/src/hb-buffer-private.hh
index 0ffb60d..67c431d 100644
--- a/src/hb-buffer-private.hh
+++ b/src/hb-buffer-private.hh
@@ -41,7 +41,7 @@
 #ifndef HB_BUFFER_MAX_LEN_MIN
 #define HB_BUFFER_MAX_LEN_MIN 8192
 #endif
-#ifndef HB_BUFFER_MAX_LEN_DEFAULT_
+#ifndef HB_BUFFER_MAX_LEN_DEFAULT
 #define HB_BUFFER_MAX_LEN_DEFAULT 0x3FFFFFFF /* Shaping more than a billion chars? Let us know! */
 #endif