diff --git a/src/mycompiler/mytype/RefType.java b/src/mycompiler/mytype/RefType.java
index 9e1ec0c2..72810d73 100755
--- a/src/mycompiler/mytype/RefType.java
+++ b/src/mycompiler/mytype/RefType.java
@@ -219,7 +219,10 @@ public class RefType extends Type implements IMatchable
     	Vector<Type> paralist = new Vector<Type>();
     	if(this.get_ParaList()!=null)for(Type t : this.get_ParaList()){
     		if(t instanceof GenericTypeVar)paralist.add(((GenericTypeVar)t).getTypePlaceHolder());
-    		else paralist.add(t);
+    		else{
+    			if(t instanceof RefType)((RefType) t).GTV2TPH();
+    			paralist.add(t);
+    		}
     	}
     	this.set_ParaList(paralist);
     }
diff --git a/src/typinferenz/SingleConstraint.java b/src/typinferenz/SingleConstraint.java
index 431f2da6..12d35320 100755
--- a/src/typinferenz/SingleConstraint.java
+++ b/src/typinferenz/SingleConstraint.java
@@ -66,6 +66,9 @@ public class SingleConstraint extends UndConstraint{
 		//{//Wenn die beiden übergebenen Typen weder RefTypes noch TypePlaceholder sind:
 		//	throw new TypinferenzException("Ein Constraint darf nur aus TypePlaceholdern und Reftypes bestehen");
 		//}
+		if(!(p1 instanceof RefType) && !(p1 instanceof TypePlaceholder))throw new DebugException("Fehler: "+p2+" kann nicht in TPH oder RefType umgewandelt werden");
+		if(!(p2 instanceof RefType) && !(p2 instanceof TypePlaceholder))throw new DebugException("Fehler: "+p2+" kann nicht in TPH oder RefType umgewandelt werden");
+		
 		constraintPair = new Pair(p1,p2);
 	}