diff --git a/gio/ChangeLog b/gio/ChangeLog
index 2367521b6..6833086e3 100644
--- a/gio/ChangeLog
+++ b/gio/ChangeLog
@@ -1,3 +1,15 @@
+2008-04-16  Matthias Clasen  <mclasen@redhat.com>
+
+	Avoid possible memory corruption in xdgmime, fd.o bug 12512,
+	reported by Joe Shaw and Federico Mena Quintero.
+
+	* xdgmime/xdgmime.c(_xdg_mime_media_type_equal): Implement.
+	(xdg_mime_media_type_equal): Turn into a wrapper around the 
+	_-prefixed version.
+
+	* xdgmime/xdgmimecache.c: Use the _-prefixed versions of comparison
+	functions throughout.
+
 2008-04-16  Michael Meeks  <michael.meeks@novell.com>
 
 	* gdesktopappinfo.c (g_desktop_app_info_new_from_filename): 
diff --git a/gio/xdgmime/xdgmime.c b/gio/xdgmime/xdgmime.c
index 0e11b070a..53e11945e 100644
--- a/gio/xdgmime/xdgmime.c
+++ b/gio/xdgmime/xdgmime.c
@@ -684,13 +684,11 @@ xdg_mime_mime_type_equal (const char *mime_a,
 }
 
 int
-xdg_mime_media_type_equal (const char *mime_a,
-			   const char *mime_b)
+_xdg_mime_media_type_equal (const char *mime_a,
+			    const char *mime_b)
 {
   char *sep;
 
-  xdg_mime_init ();
-
   sep = strchr (mime_a, '/');
   
   if (sep && strncmp (mime_a, mime_b, sep - mime_a + 1) == 0)
@@ -699,6 +697,15 @@ xdg_mime_media_type_equal (const char *mime_a,
   return 0;
 }
 
+int
+xdg_mime_media_type_equal (const char *mime_a,
+			   const char *mime_b)
+{
+  xdg_mime_init ();
+
+  return _xdg_mime_media_type_equal (mime_a, mime_b);
+}
+
 #if 1
 static int
 xdg_mime_is_super_type (const char *mime)
diff --git a/gio/xdgmime/xdgmimecache.c b/gio/xdgmime/xdgmimecache.c
index 884074e88..48dd578f2 100644
--- a/gio/xdgmime/xdgmimecache.c
+++ b/gio/xdgmime/xdgmimecache.c
@@ -297,7 +297,7 @@ cache_magic_lookup_data (XdgMimeCache *cache,
 	  for (n = 0; n < n_mime_types; n++)
 	    {
 	      if (mime_types[n] && 
-		  xdg_mime_mime_type_equal (mime_types[n], non_match))
+		  _xdg_mime_mime_type_equal (mime_types[n], non_match))
 		mime_types[n] = NULL;
 	    }
 	}
@@ -797,7 +797,7 @@ _xdg_mime_cache_mime_type_subclass (const char *mime,
 #if 1
   /* Handle supertypes */
   if (is_super_type (ubase) &&
-      xdg_mime_media_type_equal (umime, ubase))
+      _xdg_mime_media_type_equal (umime, ubase))
     return 1;
 #endif