--- tabs.module
+++ tabs.module
@@ -86,7 +86,7 @@ function tabs_pre_render_tabset($element) {
       if ((!isset($element[$key]['#tab_name']) || empty($element[$key]['#tab_name'])) && variable_get('tabs_descriptive_urls', 0)) {
         // Clean out invalid characters.
         $clean_title = preg_replace('/[^\sa-zA-Z0-9\ ]+/ ', ' ', $element[$key]['#title']);
-        $element[$key]['#tab_name'] = strtolower($clean_title);
+        $element[$key]['#tab_name'] = trim(strtolower($clean_title));
       }
       // If the tab_name is still empty, set one.
       if (!isset($element[$key]['#tab_name']) || empty($element[$key]['#tab_name'])) {