diff --git a/libfuse/include/fuse_cfg.hpp b/libfuse/include/fuse_cfg.hpp
index f1d3144f..7dd15c4a 100644
--- a/libfuse/include/fuse_cfg.hpp
+++ b/libfuse/include/fuse_cfg.hpp
@@ -3,6 +3,7 @@
 #include "int_types.h"
 
 #define FUSE_CFG_INVALID_ID -1
+#define FUSE_CFG_INVALID_UMASK -1
 
 struct fuse_cfg_t
 {