diff --git a/code/GoogleSitemap.php b/code/GoogleSitemap.php
index aaa6050..02b8ba9 100644
--- a/code/GoogleSitemap.php
+++ b/code/GoogleSitemap.php
@@ -286,6 +286,7 @@ class GoogleSitemap {
 
 				$lastEdited = $instances
 					->limit($countPerFile, ($i - 1) * $countPerFile)
+					->sort(array())
 					->max('LastEdited');
 
 				$lastModified = ($lastEdited) ? date('Y-m-d', strtotime($lastEdited)) : date('Y-m-d');
@@ -400,4 +401,4 @@ class GoogleSitemap {
 	public static function enabled() {
 		return (Config::inst()->get('GoogleSitemap', 'enabled', Config::INHERITED));
 	}  
-}
\ No newline at end of file
+}