diff --git a/AlgebraicDataflowArchitectureModel/src/simulator/Event.java b/AlgebraicDataflowArchitectureModel/src/simulator/Event.java
index 23dfafa..9cc7e6a 100644
--- a/AlgebraicDataflowArchitectureModel/src/simulator/Event.java
+++ b/AlgebraicDataflowArchitectureModel/src/simulator/Event.java
@@ -260,6 +260,9 @@
 			throws InvalidMessage, ResolvingMultipleDefinitionIsFutureWork, UnificationFailed {
 		Expression unifiedMessage = null;
 		Expression messageConstraint = null;
+		if (message != null) {
+			unifiedMessage = (Term) message.clone();
+		}
 		IResourceStateAccessor resouceStateAccessor = new IResourceStateAccessor() {
 			@Override
 			public Expression getCurrentStateAccessorFor(ChannelMember target, ChannelMember from) {