diff --git a/ChangeLog b/ChangeLog
index 9a363ed2f..6f61be418 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2008-10-26  Thomas Thurman  <tthurman@gnome.org>
+
+        * src/core/prefs.c (mouse_button_mods_handler): Ignore values
+          of .../mouse_button_modifier key if the key's missing.
+          Closes Launchpad bug #258054, Launchpad bug #266929.
+
 2008-10-23  Frederic Peters  <fpeters@0d.be>
 
 	* doc/creating_themes/C/creating-metacity-themes.xml: added missing @id
diff --git a/src/core/prefs.c b/src/core/prefs.c
index ab82c9885..267eb47b8 100644
--- a/src/core/prefs.c
+++ b/src/core/prefs.c
@@ -1381,7 +1381,7 @@ mouse_button_mods_handler (MetaPreference pref,
   meta_topic (META_DEBUG_KEYBINDINGS,
               "Mouse button modifier has new gconf value \"%s\"\n",
               string_value);
-  if (meta_ui_parse_modifier (string_value, &mods))
+  if (string_value && meta_ui_parse_modifier (string_value, &mods))
     {
       mouse_button_mods = mods;
     }