diff --git a/Doctrine/ORM/Query.php b/Doctrine/ORM/Query.php
index 4c755d0..b8a6766 100644
--- a/Doctrine/ORM/Query.php
+++ b/Doctrine/ORM/Query.php
@@ -244,6 +244,10 @@ final class Query extends AbstractQuery
             if (is_object($value) && $this->_em->getMetadataFactory()->hasMetadataFor(get_class($value))) {
                 //TODO: Check that $value is MANAGED?
                 $values = $this->_em->getUnitOfWork()->getEntityIdentifier($value);
+                if (! $values) {
+                    $class = $this->_em->getClassMetadata(get_class($value));
+                    $values = $class->getIdentifierValues($value);
+                }
                 $sqlPositions = $paramMappings[$key];
                 $sqlParams += array_combine((array)$sqlPositions, $values);
             } else {