diff --git a/libs/plugins/function.debug.php b/libs/plugins/function.debug.php
index 2452d625..200b9669 100644
--- a/libs/plugins/function.debug.php
+++ b/libs/plugins/function.debug.php
@@ -23,8 +23,8 @@
  */
 function smarty_function_debug($params, &$smarty)
 {
-    if($params['output']) {
-        $smarty->assign('_smarty_debug_output',$params['output']);
+    if (isset($params['output'])) {
+        $smarty->assign('_smarty_debug_output', $params['output']);
     }
     require_once(SMARTY_DIR . 'core' . DIRECTORY_SEPARATOR . 'core.display_debug_console.php');
     return smarty_core_display_debug_console(null, $smarty);