--- a/src/common/memgzio.c
+++ b/src/common/memgzio.c
@@ -1,3 +1,4 @@
+#define OF(x) x
 /* gzio.c -- IO on .gz files
  * Copyright (C) 1995-2002 Jean-loup Gailly.
  * For conditions of distribution and use, see copyright notice in zlib.h