use = instead of +=
diff --git a/system/libraries/Cache/drivers/Cache_redis.php b/system/libraries/Cache/drivers/Cache_redis.php
index a35fbf6..43e2177 100644
--- a/system/libraries/Cache/drivers/Cache_redis.php
+++ b/system/libraries/Cache/drivers/Cache_redis.php
@@ -270,7 +270,7 @@
 
 		if ($CI->config->load('redis', TRUE, TRUE))
 		{
-			$config += $CI->config->item('redis');
+			$config = $CI->config->item('redis');
 		}
 
 		$config = array_merge(self::$_default_config, $config);