diff --git includes/theme.inc includes/theme.inc
index c501586..dd497bd 100644
--- includes/theme.inc
+++ includes/theme.inc
@@ -982,7 +982,7 @@ function drupal_find_theme_functions($cache, $prefixes) {
         $matches = preg_grep('/^' . $prefix . '_' . $pattern . '/', $functions['user']);
         if ($matches) {
           foreach ($matches as $match) {
-            $new_hook = str_replace($prefix . '_', '', $match);
+            $new_hook = preg_replace("/^" . $prefix . "_/", "", $match);
             $arg_name = isset($info['variables']) ? 'variables' : 'render element';
             $implementations[$new_hook] = array(
               'function' => $match,