diff --git a/de.prob.core/src/de/prob/core/domainobjects/ltl/CounterExample.java b/de.prob.core/src/de/prob/core/domainobjects/ltl/CounterExample.java
index 4c45e0f2ae892af17a5740468fe492d9a6511de1..43dffabb86cb780dba94ead192159ead771e8eed 100644
--- a/de.prob.core/src/de/prob/core/domainobjects/ltl/CounterExample.java
+++ b/de.prob.core/src/de/prob/core/domainobjects/ltl/CounterExample.java
@@ -146,7 +146,7 @@ public class CounterExample {
 
 				final String name = atomicFormulaNames[atomicId];
 
-				Logger.assertProB("CounterExample invalid",
+				Logger.assertProB("CounterExample functor invalid: "+functor,
 						values.length == predicateValues.get(atomicId).size());
 
 				for (int i = 0; i < predicateValues.get(atomicId).size(); i++) {