diff '--color=always' '--color=never' -Naurd mousepad-0.4.1_old/mousepad/mousepad-file.c mousepad-0.4.1_new/mousepad/mousepad-file.c
--- mousepad-0.4.1_old/mousepad/mousepad-file.c	2018-06-01 04:38:34.000000000 +0500
+++ mousepad-0.4.1_new/mousepad/mousepad-file.c	2019-02-16 19:01:01.650292724 +0500
@@ -450,6 +450,7 @@
 mousepad_file_guess_language (MousepadFile *file)
 {
   gchar             *content_type;
+  gchar             *basename;
   gboolean           result_uncertain;
   GtkSourceLanguage *language = NULL;
 
@@ -462,11 +463,13 @@
 
   if (G_LIKELY (content_type != NULL || file->filename != NULL))
     {
+      basename = g_path_get_basename (file->filename);
       language = gtk_source_language_manager_guess_language (gtk_source_language_manager_get_default (),
-                                                             file->filename,
+                                                             basename,
                                                              content_type);
     }
 
+  g_free (basename);
   g_free (content_type);
 
   return language;