diff --git a/AlgebraicDataflowArchitectureModel/src/models/controlFlowModel/ObjectNodeAttribute.java b/AlgebraicDataflowArchitectureModel/src/models/controlFlowModel/ObjectNodeAttribute.java
index 8aa9730..0930054 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/controlFlowModel/ObjectNodeAttribute.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/controlFlowModel/ObjectNodeAttribute.java
@@ -6,7 +6,7 @@
  * {@link ObjectNodeAttribute} represents an attribute that the linked object node in a control-flow graph has.
  */
 public class ObjectNodeAttribute extends NodeAttribute {
-	private ObjectNode objectNode = null;
+	private final ObjectNode objectNode;
 	private String shapeStyle = "";
 	
 	public ObjectNodeAttribute(final ObjectNode objectNode) {