diff --git a/io_posix.cpp b/io_posix.cpp
index ccb75d68..1a979f18 100644
--- a/io_posix.cpp
+++ b/io_posix.cpp
@@ -44,6 +44,13 @@ mapped_file::mapped_file (const ::cruft::posix::fd &src, int mflags)
 }
 
 
+//-----------------------------------------------------------------------------
+mapped_file::mapped_file (cruft::mapped_file &&rhs) noexcept
+  : m_data (std::exchange (rhs.m_data, nullptr))
+  , m_size (std::exchange (rhs.m_size, 0))
+{ ; }
+
+
 //----------------------------------------------------------------------------
 mapped_file::~mapped_file ()
 {
diff --git a/io_posix.hpp b/io_posix.hpp
index 196d63e0..9d165097 100644
--- a/io_posix.hpp
+++ b/io_posix.hpp
@@ -45,7 +45,7 @@ namespace cruft {
             mapped_file (const mapped_file&) = delete;
             mapped_file& operator= (const mapped_file&) = delete;
 
-            mapped_file (const mapped_file&&) noexcept;
+            mapped_file (mapped_file&&) noexcept;
             mapped_file& operator= (mapped_file&&) noexcept;
 
             ~mapped_file ();