diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
index 328d7bc35..e4b2bf4da 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
@@ -1217,7 +1217,7 @@ class ClassMetadataInfo implements ClassMetadata
 
             $uniqueContraintColumns = array();
             foreach ($mapping['joinColumns'] as $key => &$joinColumn) {
-                if ($mapping['type'] === self::ONE_TO_ONE) {
+                if ($mapping['type'] === self::ONE_TO_ONE && ! $this->isInheritanceTypeSingleTable()) {
                     if (count($mapping['joinColumns']) == 1) {
                         $joinColumn['unique'] = true;
                     } else {