--- theme.inc       2009-01-12 14:45:33.000000000 -0400
+++ theme.inc   2009-03-12 14:33:51.000000000 -0400
@@ -1717,8 +1717,17 @@
 */
function template_preprocess_page(&$variables) {
  // Add favicon
+  if ( strtolower(substr(theme_get_setting('favicon'),-4)) == ".png" ) {
+    $icontype = 'image/png';
+  }
+  elseif ( strtolower(substr(theme_get_setting('favicon'),-4)) == ".gif" ) {
+    $icontype = 'image/gif';
+  }
+  else {
+    $icontype = 'image/x-icon'; //'image/vnd.microsoft.icon' is official, but not widely supported.
+  }
  if (theme_get_setting('toggle_favicon')) {
-    drupal_set_html_head('<link rel="shortcut icon" href="'. check_url(theme_get_setting('favicon')) .'" type="image/x-icon" />');
+    drupal_set_html_head('<link rel="shortcut icon" href="'. check_url(theme_get_setting('favicon')) .'" type="' . $icontype . '" />');
  }

  global $theme;