diff --git a/system/libs/pot/OTS_DB_MySQL.php b/system/libs/pot/OTS_DB_MySQL.php
index 9e584e6a..0e51dc09 100644
--- a/system/libs/pot/OTS_DB_MySQL.php
+++ b/system/libs/pot/OTS_DB_MySQL.php
@@ -100,7 +100,7 @@ class OTS_DB_MySQL extends OTS_Base_DB
         }
 
 		global $cache, $config;
-		if($cache->enabled()) {
+		if(isset($cache) && $cache->enabled()) {
 			$tmp = null;
 			$need_revalidation = true;
 			if($cache->fetch('database_checksum', $tmp) && $tmp) {
@@ -129,7 +129,7 @@ class OTS_DB_MySQL extends OTS_Base_DB
 	public function __destruct()
     {
 		global $cache, $config;
-		if($cache->enabled()) {
+		if(isset($cache) && $cache->enabled()) {
 			$cache->set('database_tables', serialize($this->has_table_cache));
 			$cache->set('database_columns', serialize($this->has_column_cache));
 			$cache->set('database_checksum', serialize(sha1($config['database_host'] . '.' . $config['database_name'])));