diff --git a/library/includes/page_header.php b/library/includes/page_header.php
index c1ca64063..931ab6b5e 100644
--- a/library/includes/page_header.php
+++ b/library/includes/page_header.php
@@ -125,7 +125,8 @@ $template->assign_vars(array(
 // The following assigns all _common_ variables that may be used at any point in a template
 $template->assign_vars(array(
     'SIMPLE_HEADER' => !empty($gen_simple_header),
-    'CONTENT_ENCODING' => $bb_cfg['lang'][$userdata['user_lang']]['encoding'],
+    'CONTENT_ENCODING' => isset($bb_cfg['lang'][$userdata['user_lang']]['encoding']) ?
+        $bb_cfg['lang'][$userdata['user_lang']]['encoding'] : 'utf-8',
 
     'IN_ADMIN' => defined('IN_ADMIN'),
     'SHOW_ADS' => (!$logged_in || isset($bb_cfg['show_ads_users'][$user->id]) || (!IS_AM && $user->show_ads)),
diff --git a/library/includes/sessions.php b/library/includes/sessions.php
index 8f8c7ffa4..21a0ee9d3 100644
--- a/library/includes/sessions.php
+++ b/library/includes/sessions.php
@@ -562,7 +562,8 @@ class user_common
         }
 
         require(LANG_DIR . 'main.php');
-        setlocale(LC_ALL, $bb_cfg['lang'][$this->data['user_lang']]['locale']);
+        setlocale(LC_ALL, isset($bb_cfg['lang'][$this->data['user_lang']]['locale']) ?
+            $bb_cfg['lang'][$this->data['user_lang']]['locale'] : 'en_US.UTF-8');
 
         $theme = setup_style();
         $DeltaTime = new Date_Delta();