diff --git a/posix/flock.cpp b/posix/flock.cpp
index d3fa0f43..91d8e9f9 100644
--- a/posix/flock.cpp
+++ b/posix/flock.cpp
@@ -16,6 +16,12 @@ using flock_  = cruft::posix::flock;
 
 
 ///////////////////////////////////////////////////////////////////////////////
+flock_::flock (cruft::posix::fd const &_fd, int const _operation)
+    : flock (_fd.dup (), _operation)
+{ ; }
+
+
+//-----------------------------------------------------------------------------
 flock_::flock (
     cruft::posix::fd &&_fd,
     int operation