diff --git a/plugins/org.eclipse.elk.alg.layered/src/org/eclipse/elk/alg/layered/compound/CompoundGraphPreprocessor.java b/plugins/org.eclipse.elk.alg.layered/src/org/eclipse/elk/alg/layered/compound/CompoundGraphPreprocessor.java
index e7ae3aefea..e592f9027b 100644
--- a/plugins/org.eclipse.elk.alg.layered/src/org/eclipse/elk/alg/layered/compound/CompoundGraphPreprocessor.java
+++ b/plugins/org.eclipse.elk.alg.layered/src/org/eclipse/elk/alg/layered/compound/CompoundGraphPreprocessor.java
@@ -176,7 +176,7 @@ private List<ExternalPort> transformHierarchyEdges(final LGraph graph, final LNo
                         if (dummyNode == null) {
                             dummyNode = LGraphUtil.createExternalPortDummy(port,
                                     portConstraints, port.getSide(), -port.getNetFlow(),
-                                    null, null, port.getSize(),
+                                    null, new KVector(), port.getSize(),
                                     nestedGraph.getProperty(LayeredOptions.DIRECTION), nestedGraph);
                             dummyNode.setProperty(InternalProperties.ORIGIN, port);
                             dummyNodeMap.put(port, dummyNode);