diff --git a/src/de/dhbwstuttgart/syntaxtree/factory/Unify_FC_TTO_Builder.java b/src/de/dhbwstuttgart/syntaxtree/factory/Unify_FC_TTO_Builder.java
index 524e729e..d8276f99 100644
--- a/src/de/dhbwstuttgart/syntaxtree/factory/Unify_FC_TTO_Builder.java
+++ b/src/de/dhbwstuttgart/syntaxtree/factory/Unify_FC_TTO_Builder.java
@@ -14,11 +14,13 @@ public class Unify_FC_TTO_Builder {
 	
 	public void AddInheritance(Type t1, Type t2) {
 		if(t1 instanceof RefType)
-			classes.add(new Class(t1.get_Name(), t1.getOffset()));
+			if(!classes.stream().anyMatch(x -> x.getName().equals(t1.getName())))
+				classes.add(new Class(t1.get_Name(), t1.getOffset()));
 		
 		if(t2 instanceof RefType)
-			classes.add(new Class(t2.get_Name(), t2.getOffset()));
-		
+			if(!classes.stream().anyMatch(x -> x.getName().equals(t2.getName())))
+				classes.add(new Class(t2.get_Name(), t2.getOffset()));
+
 		fc.add(new Pair(t1, t2));
 	}
 	
diff --git a/test/unify/UnifyTest.java b/test/unify/UnifyTest.java
index 3c5792a3..7e3cff74 100644
--- a/test/unify/UnifyTest.java
+++ b/test/unify/UnifyTest.java
@@ -50,8 +50,9 @@ public class UnifyTest extends Unify {
 		
 		Set<MPair> eq = new HashSet<MPair>();
 		Set<Set<MPair>> expected = new HashSet<>();
+		expected.add(new HashSet<>());
 		Set<Set<MPair>> actual = unify(eq, fc);
-		Assert.assertEquals(actual, expected);
+		Assert.assertEquals(expected, actual);
 		
 		/*
 		 * Test 2: