diff --git a/src/fuse_open.cpp b/src/fuse_open.cpp
index 975e0243..d96c1026 100644
--- a/src/fuse_open.cpp
+++ b/src/fuse_open.cpp
@@ -261,6 +261,14 @@ namespace l
   }
 }
 
+constexpr
+uint64_t
+combine(PassthroughEnum e,
+        uint64_t        m)
+{
+  return ((((uint64_t)e) << 32) | (m & O_ACCMODE));
+}
+
 namespace FUSE
 {
   int