diff --git a/src/de/dhbwstuttgart/strucTypes/Construct.java b/src/de/dhbwstuttgart/strucTypes/Construct.java
index ac5aa85a..96cc7507 100644
--- a/src/de/dhbwstuttgart/strucTypes/Construct.java
+++ b/src/de/dhbwstuttgart/strucTypes/Construct.java
@@ -2,7 +2,9 @@ package de.dhbwstuttgart.strucTypes;
 
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import org.antlr.v4.runtime.Token;
 
@@ -29,7 +31,7 @@ public class Construct extends DefaultASTVisitor {
 
 	private List<SubTypeConstraint> subTypeConstraints = new ArrayList<>();
 	private ConstraintsSet constraintsSet = new ConstraintsSet();
-	private List<RefTypeOrTPHOrWildcardOrGeneric> newInterf = new ArrayList<>();
+	private Set<RefTypeOrTPHOrWildcardOrGeneric> newInterf = new HashSet<>();
 	private InferredTypes inferredTypes = new InferredTypes();
 	private List<ClassOrInterface> constructedInterfaces = new ArrayList<>();