diff --git a/UPGRADE.md b/UPGRADE.md
index 1594f0c98..1b7e8a90c 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,3 +1,11 @@
+# Upgrade to 2.4
+
+## OnFlush and PreFlush event always called
+
+Before 2.4  the preFlush and onFlush events were only called when there were
+actually entities that changed. Now these events are called no matter if there
+are entities in the UoW or changes are found.
+
 # Upgrade to 2.3
 
 ## EntityManager#find() not calls EntityRepository#find() anymore
diff --git a/lib/Doctrine/ORM/UnitOfWork.php b/lib/Doctrine/ORM/UnitOfWork.php
index 99c66472c..24f05748d 100644
--- a/lib/Doctrine/ORM/UnitOfWork.php
+++ b/lib/Doctrine/ORM/UnitOfWork.php
@@ -287,6 +287,9 @@ class UnitOfWork implements PropertyChangedListener
                 $this->collectionUpdates ||
                 $this->collectionDeletions ||
                 $this->orphanRemovals)) {
+            $this->dispatchOnFlushEvent();
+            $this->dispatchPostFlushEvent();
+
             return; // Nothing to do.
         }
 
@@ -296,10 +299,7 @@ class UnitOfWork implements PropertyChangedListener
             }
         }
 
-        // Raise onFlush
-        if ($this->evm->hasListeners(Events::onFlush)) {
-            $this->evm->dispatchEvent(Events::onFlush, new Event\OnFlushEventArgs($this->em));
-        }
+        $this->dispatchOnFlushEvent();
 
         // Now we need a commit order to maintain referential integrity
         $commitOrder = $this->getCommitOrder();
@@ -354,10 +354,7 @@ class UnitOfWork implements PropertyChangedListener
             $coll->takeSnapshot();
         }
 
-        // Raise postFlush
-        if ($this->evm->hasListeners(Events::postFlush)) {
-            $this->evm->dispatchEvent(Events::postFlush, new Event\PostFlushEventArgs($this->em));
-        }
+        $this->dispatchPostFlushEvent();
 
         // Clear up
         $this->entityInsertions =
@@ -3153,4 +3150,18 @@ class UnitOfWork implements PropertyChangedListener
 
         return isset($this->readOnlyObjects[spl_object_hash($object)]);
     }
+
+    private function dispatchOnFlushEvent()
+    {
+        if ($this->evm->hasListeners(Events::onFlush)) {
+            $this->evm->dispatchEvent(Events::onFlush, new Event\OnFlushEventArgs($this->em));
+        }
+    }
+
+    private function dispatchPostFlushEvent()
+    {
+        if ($this->evm->hasListeners(Events::postFlush)) {
+            $this->evm->dispatchEvent(Events::postFlush, new Event\PostFlushEventArgs($this->em));
+        }
+    }
 }
diff --git a/tests/Doctrine/Tests/ORM/Functional/FlushEventTest.php b/tests/Doctrine/Tests/ORM/Functional/FlushEventTest.php
index 8167e8587..156e89b0e 100644
--- a/tests/Doctrine/Tests/ORM/Functional/FlushEventTest.php
+++ b/tests/Doctrine/Tests/ORM/Functional/FlushEventTest.php
@@ -48,6 +48,26 @@ class FlushEventTest extends \Doctrine\Tests\OrmFunctionalTestCase
         //echo "SECOND FLUSH";
         //$this->_em->flush();
     }
+
+    /**
+     * @group DDC-2173
+     */
+    public function testPreAndOnFlushCalledAlways()
+    {
+        $listener = new OnFlushCalledListener();
+        $this->_em->getEventManager()->addEventListener(Events::onFlush, $listener);
+        $this->_em->getEventManager()->addEventListener(Events::preFlush, $listener);
+
+        $this->_em->flush();
+
+        $this->assertEquals(1, $listener->preFlush);
+        $this->assertEquals(1, $listener->onFlush);
+
+        $this->_em->flush();
+
+        $this->assertEquals(2, $listener->preFlush);
+        $this->assertEquals(2, $listener->onFlush);
+    }
 }
 
 class OnFlushListener
@@ -91,4 +111,18 @@ class OnFlushListener
     }
 }
 
+class OnFlushCalledListener
+{
+    public $preFlush = 0;
+    public $onFlush = 0;
 
+    public function preFlush($args)
+    {
+        $this->preFlush++;
+    }
+
+    public function onFlush($args)
+    {
+        $this->onFlush++;
+    }
+}