diff --git a/lib/Doctrine/ORM/UnitOfWork.php b/lib/Doctrine/ORM/UnitOfWork.php
index 0ebdedcb9..bf491084e 100644
--- a/lib/Doctrine/ORM/UnitOfWork.php
+++ b/lib/Doctrine/ORM/UnitOfWork.php
@@ -620,6 +620,15 @@ class UnitOfWork implements PropertyChangedListener
         foreach ($class->associationMappings as $field => $assoc) {
             if (($val = $class->reflFields[$field]->getValue($entity)) !== null) {
                 $this->computeAssociationChanges($assoc, $val);
+                if (!isset($this->entityChangeSets[$oid]) &&
+                    $assoc['isOwningSide'] &&
+                    $assoc['type'] == ClassMetadata::MANY_TO_MANY &&
+                    $val instanceof PersistentCollection &&
+                    $val->isDirty()) {
+                    $this->entityChangeSets[$oid]   = array();
+                    $this->originalEntityData[$oid] = $actualData;
+                    $this->entityUpdates[$oid]      = $entity;
+                }
             }
         }
     }