diff --git a/app/code/core/Mage/Review/Model/Resource/Review.php b/app/code/core/Mage/Review/Model/Resource/Review.php
index f2cf190beec..2fc6c2534b9 100644
--- a/app/code/core/Mage/Review/Model/Resource/Review.php
+++ b/app/code/core/Mage/Review/Model/Resource/Review.php
@@ -357,7 +357,7 @@ public function aggregate($object)
 
             $writeAdapter->beginTransaction();
             try {
-                if ($oldData['primary_id'] > 0) {
+                if (isset($oldData['primary_id']) && $oldData['primary_id'] > 0) {
                     $condition = ["{$this->_aggregateTable}.primary_id = ?" => $oldData['primary_id']];
                     $writeAdapter->update($this->_aggregateTable, $data->getData(), $condition);
                 } else {