diff --git a/src/main/java/gr/uom/java/xmi/decomposition/VariableReplacementAnalysis.java b/src/main/java/gr/uom/java/xmi/decomposition/VariableReplacementAnalysis.java
index 2a9de263b..cf626e7ed 100644
--- a/src/main/java/gr/uom/java/xmi/decomposition/VariableReplacementAnalysis.java
+++ b/src/main/java/gr/uom/java/xmi/decomposition/VariableReplacementAnalysis.java
@@ -499,7 +499,7 @@ private boolean equalType(VariableDeclaration removedVariable, VariableDeclarati
 		}
 		if(classDiff instanceof UMLClassBaseDiff) {
 			UMLTypeParameterListDiff listDiff = ((UMLClassBaseDiff)classDiff).getTypeParameterDiffList();
-			if(removedVariable.getType().matchWithParentClassTypeParameterChange(addedVariable.getType(), listDiff.getTypeParameterDiffs())) {
+			if(listDiff != null && removedVariable.getType().matchWithParentClassTypeParameterChange(addedVariable.getType(), listDiff.getTypeParameterDiffs())) {
 				return true;
 			}
 		}