diff --git a/dlib/dir_nav/dir_nav_kernel_1.h b/dlib/dir_nav/dir_nav_kernel_1.h
index 115f9adf0..af1c34bc6 100644
--- a/dlib/dir_nav/dir_nav_kernel_1.h
+++ b/dlib/dir_nav/dir_nav_kernel_1.h
@@ -101,6 +101,9 @@ namespace dlib
         inline  const std::string& full_name (
         ) const { return state.full_name; }
 
+        operator std::string (
+        ) const { return full_name(); }
+
         inline uint64 size (
         ) const { return state.file_size; }
 
diff --git a/dlib/dir_nav/dir_nav_kernel_2.h b/dlib/dir_nav/dir_nav_kernel_2.h
index 5f8f31df5..cb433da00 100644
--- a/dlib/dir_nav/dir_nav_kernel_2.h
+++ b/dlib/dir_nav/dir_nav_kernel_2.h
@@ -109,6 +109,9 @@ namespace dlib
         inline uint64 size (
         ) const { return state.file_size; }
 
+        operator std::string (
+        ) const { return full_name(); }
+
         bool operator == (
             const file& rhs
         ) const;
diff --git a/dlib/dir_nav/dir_nav_kernel_abstract.h b/dlib/dir_nav/dir_nav_kernel_abstract.h
index 147641f8c..8f237e42e 100644
--- a/dlib/dir_nav/dir_nav_kernel_abstract.h
+++ b/dlib/dir_nav/dir_nav_kernel_abstract.h
@@ -139,6 +139,14 @@ namespace dlib
                 - returns the size of this file in bytes.
         !*/
 
+        operator std::string (
+        ) const; 
+        /*!
+            ensures
+                - returns full_name()
+                  (i.e. provides an implicit conversion to string from dlib::file)
+        !*/
+
         file& operator= (
             const file& rhs
         );