diff --git a/3d-viewer/3d_cache/3d_filename_resolver.cpp b/3d-viewer/3d_cache/3d_filename_resolver.cpp
index b4a885045c..cbd7f56e37 100644
--- a/3d-viewer/3d_cache/3d_filename_resolver.cpp
+++ b/3d-viewer/3d_cache/3d_filename_resolver.cpp
@@ -463,6 +463,14 @@ wxString S3D_FILENAME_RESOLVER::ShortenPath( const wxString& aFullPathName )
         ++sL;
     }
 
+#ifdef _WIN32
+    // it is strange to convert an MSWin full path to use the
+    // UNIX separator but this is done for consistency and can
+    // be helpful even when transferring project files from
+    // MSWin to *NIX.
+    fname.Replace( wxT( "\\" ), wxT( "/" ) );
+#endif
+
     return fname;
 }