diff --git a/core/model/SiteTree.php b/core/model/SiteTree.php
index 3fed86725..5f1b67b31 100644
--- a/core/model/SiteTree.php
+++ b/core/model/SiteTree.php
@@ -777,7 +777,7 @@ class SiteTree extends DataObject {
 			'';
 
 		$count = 1;
-		while(DataObject::get_one("SiteTree", "URLSegment = '$this->URLSegment' $idFilter")) {
+		while(class_exists($this->URLSegment) || DataObject::get_one("SiteTree", "URLSegment = '$this->URLSegment' $idFilter")) {
 			$count++;
 			$this->URLSegment = ereg_replace('-[0-9]+$','', $this->URLSegment) . "-$count";
 		}