diff --git a/source/java/org/alfresco/repo/lock/mem/AbstractLockStore.java b/source/java/org/alfresco/repo/lock/mem/AbstractLockStore.java
index 97158681d9..95ece667c5 100644
--- a/source/java/org/alfresco/repo/lock/mem/AbstractLockStore.java
+++ b/source/java/org/alfresco/repo/lock/mem/AbstractLockStore.java
@@ -24,6 +24,7 @@ import java.util.concurrent.ConcurrentMap;
 
 import org.alfresco.repo.transaction.TransactionalResourceHelper;
 import org.alfresco.service.cmr.repository.NodeRef;
+import org.alfresco.util.ParameterCheck;
 import org.springframework.dao.ConcurrencyFailureException;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
 
@@ -44,6 +45,7 @@ public abstract class AbstractLockStore<T extends ConcurrentMap<NodeRef, LockSta
     @Override
     public LockState get(NodeRef nodeRef)
     {
+        ParameterCheck.mandatory("nodeRef", nodeRef);
         LockState lockState;
         Map<NodeRef, LockState> txMap = getTxMap();
         if (txMap != null && txMap.containsKey(nodeRef))
diff --git a/source/test-java/org/alfresco/repo/rendition/RenditionServiceIntegrationTest.java b/source/test-java/org/alfresco/repo/rendition/RenditionServiceIntegrationTest.java
index d1faffdcc6..510f065d39 100644
--- a/source/test-java/org/alfresco/repo/rendition/RenditionServiceIntegrationTest.java
+++ b/source/test-java/org/alfresco/repo/rendition/RenditionServiceIntegrationTest.java
@@ -647,6 +647,11 @@ public class RenditionServiceIntegrationTest extends BaseAlfrescoSpringTest
      * @throws Exception
      */
     protected void renderPdfDocumentLongRunningTest(AbstractNodeModifyingRunnable nodeModifyingRunnable) throws Exception
+    {
+        renderPdfDocumentLongRunningTest(nodeModifyingRunnable, false);
+    }
+    
+    protected void renderPdfDocumentLongRunningTest(AbstractNodeModifyingRunnable nodeModifyingRunnable, boolean joinNodeModifyingThread) throws Exception
     {
         this.setComplete();
         this.endTransaction();
@@ -697,6 +702,11 @@ public class RenditionServiceIntegrationTest extends BaseAlfrescoSpringTest
         // Give a moment for roll back of rendition and commit of node modification to occur
         Thread.sleep(3000);
         
+        if (joinNodeModifyingThread)
+        {
+            nodeModifyingThread.join();
+        }
+        
         // Note that the node modification is retried on failure by RetryingTransactionHelper
         // and will always succeed after the rendition is complete, but due to the 
         // sleep in AbstractNodeModifyingRunnable isModificationUnblocked will still 
@@ -732,7 +742,7 @@ public class RenditionServiceIntegrationTest extends BaseAlfrescoSpringTest
                     checkOutCheckInService.checkout(nodeWithDocContent);
                 }
             };
-            renderPdfDocumentLongRunningTest(new CheckoutRunnable(nodeWithDocContent));
+            renderPdfDocumentLongRunningTest(new CheckoutRunnable(nodeWithDocContent), true);
         }
         finally
         {