diff --git a/plugins/org.eclipse.wst.common.emfworkbench.integration/src/org/eclipse/wst/common/internal/emfworkbench/integration/EditModel.java b/plugins/org.eclipse.wst.common.emfworkbench.integration/src/org/eclipse/wst/common/internal/emfworkbench/integration/EditModel.java
index 0cdd275..0b0a6cb 100644
--- a/plugins/org.eclipse.wst.common.emfworkbench.integration/src/org/eclipse/wst/common/internal/emfworkbench/integration/EditModel.java
+++ b/plugins/org.eclipse.wst.common.emfworkbench.integration/src/org/eclipse/wst/common/internal/emfworkbench/integration/EditModel.java
@@ -505,15 +505,18 @@
 			addEditModelResource(res);
 		}
 		Collection resourceExtensions = EditModelRegistry.getInstance().getEditModelExtensions(getEditModelID());
-		if (resourceExtensions.isEmpty()) {
-			knownResourceExtensions = Collections.EMPTY_LIST;
-		} else {
+		/* bug 170690 - initialize knownResourceExtensions if necessary, and change reference from iter to it */
+		if (knownResourceExtensions == null)
+		{
+			knownResourceExtensions = new ArrayList();
+		}
+		if (!resourceExtensions.isEmpty())
+		{
 			knownResourceExtensions.addAll(resourceExtensions);
 			Iterator it = resourceExtensions.iterator();
 			ResourceSetWorkbenchEditSynchronizer sync = (ResourceSetWorkbenchEditSynchronizer) getEmfContext().getResourceSet().getSynchronizer();
 			while (it.hasNext()) {
-				String extension = (String) iter.next();
-				sync.enableAutoload(extension);
+				sync.enableAutoload(it.next().toString());
 			}
 		}
 	}