diff --git a/libs/Smarty.class.php b/libs/Smarty.class.php
index 48e33a5b..2310f203 100644
--- a/libs/Smarty.class.php
+++ b/libs/Smarty.class.php
@@ -1204,7 +1204,7 @@ class Smarty
         }
 
         if (!$this->debugging && $this->debugging_ctrl == 'URL'
-               && strstr($GLOBALS['HTTP_SERVER_VARS']['QUERY_STRING'], $this->_smarty_debug_id)) {
+               && @strstr($GLOBALS['HTTP_SERVER_VARS']['QUERY_STRING'], $this->_smarty_debug_id)) {
             // enable debugging from URL
             $this->debugging = true;
         }
@@ -1266,7 +1266,7 @@ class Smarty
                         $_smarty_results .= smarty_core_display_debug_console($_params, $this);
                     }
                     if ($this->cache_modified_check) {
-                        $_last_modified_date = substr($GLOBALS['HTTP_SERVER_VARS']['HTTP_IF_MODIFIED_SINCE'], 0, strpos($GLOBALS['HTTP_SERVER_VARS']['HTTP_IF_MODIFIED_SINCE'], 'GMT') + 3);
+                        $_last_modified_date = @substr($GLOBALS['HTTP_SERVER_VARS']['HTTP_IF_MODIFIED_SINCE'], 0, strpos($GLOBALS['HTTP_SERVER_VARS']['HTTP_IF_MODIFIED_SINCE'], 'GMT') + 3);
                         $_gmt_mtime = gmdate('D, d M Y H:i:s', $this->_cache_info['timestamp']).' GMT';
                         if (@count($this->_cache_info['insert_tags']) == 0
                             && !$this->_cache_serials