diff --git a/src/org/rascalmpl/interpreter/matching/TypedVariablePattern.java b/src/org/rascalmpl/interpreter/matching/TypedVariablePattern.java
index ef64cf610df..e94a28eddaa 100644
--- a/src/org/rascalmpl/interpreter/matching/TypedVariablePattern.java
+++ b/src/org/rascalmpl/interpreter/matching/TypedVariablePattern.java
@@ -113,7 +113,7 @@ public boolean next() {
 					
 					if (dynMatchType.isOpen()) {
 						// type parameter hygiene required (consider self-application of a function like `&T id(&T v) = v`)
-						dynMatchType = AbstractFunction.renameType(dynMatchType, new HashMap<>());
+						dynMatchType = AbstractFunction.renameType(dynMatchType, new HashMap<>(), ctx.getCurrentAST().getLocation());
 					}
 
 					if (!declaredType.match(dynMatchType, dynBindings)) {
@@ -134,7 +134,7 @@ public boolean next() {
 			Type dynType = subject.getValue().getType();
 			if (dynType.isOpen()) {
 				// type parameter hygiene required (consider self-application of a function like `&T id(&T v) = v`)
-				dynType = AbstractFunction.renameType(dynType, new HashMap<>());
+				dynType = AbstractFunction.renameType(dynType, new HashMap<>(), ctx.getCurrentAST().getLocation());
 			}
 
 			if (!dynType.isSubtypeOf(declaredType.instantiate(ctx.getCurrentEnvt().getDynamicTypeBindings()))) {
diff --git a/src/org/rascalmpl/interpreter/result/AbstractFunction.java b/src/org/rascalmpl/interpreter/result/AbstractFunction.java
index 7a453732d21..a0a29e38fc2 100644
--- a/src/org/rascalmpl/interpreter/result/AbstractFunction.java
+++ b/src/org/rascalmpl/interpreter/result/AbstractFunction.java
@@ -24,8 +24,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
-import java.util.UUID;
-
 import org.rascalmpl.ast.AbstractAST;
 import org.rascalmpl.ast.Expression;
 import org.rascalmpl.ast.FunctionDeclaration;
@@ -45,6 +43,7 @@
 import io.usethesource.vallang.IConstructor;
 import io.usethesource.vallang.IExternalValue;
 import io.usethesource.vallang.IListWriter;
+import io.usethesource.vallang.ISourceLocation;
 import io.usethesource.vallang.IValue;
 import io.usethesource.vallang.IValueFactory;
 import io.usethesource.vallang.IWithKeywordParameters;
@@ -347,8 +346,9 @@ protected Type bindTypeParameters(Type actualStaticTypes, IValue[] actuals, Type
 		    if (actualStaticTypes.isOpen()) {
 			    // we have to make the environment hygenic now, because the caller scope
 			    // may have the same type variable names as the current scope
-			    actualStaticTypes = renameType(actualStaticTypes, renamings);
+			    actualStaticTypes = renameType(actualStaticTypes, renamings, env.getLocation());
 			}
+
 			
 			Map<Type, Type> staticBindings = new HashMap<Type, Type>();
 			
@@ -394,13 +394,13 @@ protected static Type unrenameType(Map<Type, Type> renamings, Type resultType) {
 	    return resultType;
 	}
 	  
-    public static Type renameType(Type actualTypes, Map<Type, Type> renamings) {
+    public static Type renameType(Type actualTypes, Map<Type, Type> renamings, ISourceLocation uniquePrefix) {
         actualTypes.match(TypeFactory.getInstance().voidType(), renamings);
         
         // rename all the bound type parameters
         for (Entry<Type,Type> entry : renamings.entrySet()) {
             Type key = entry.getKey();
-            renamings.put(key, TypeFactory.getInstance().parameterType(key.getName() + ":" + UUID.randomUUID().toString(), key.getBound()));
+            renamings.put(key, TypeFactory.getInstance().parameterType(key.getName() + ":" + uniquePrefix, key.getBound()));
         }
         actualTypes = actualTypes.instantiate(renamings);
         return actualTypes;
diff --git a/src/org/rascalmpl/interpreter/result/NamedFunction.java b/src/org/rascalmpl/interpreter/result/NamedFunction.java
index d6f48776587..4323f410129 100644
--- a/src/org/rascalmpl/interpreter/result/NamedFunction.java
+++ b/src/org/rascalmpl/interpreter/result/NamedFunction.java
@@ -164,7 +164,7 @@ protected void checkReturnTypeIsNotVoid(List<Expression> formals, IValue[] actua
         Map<Type, Type> bindings = new HashMap<>();
         
         for (int i = 0; i < actuals.length; i++) {
-            formals.get(i).typeOf(declarationEnvironment, getEval(), false).match(renameType(actuals[i].getType(), renamings), bindings);
+            formals.get(i).typeOf(declarationEnvironment, getEval(), false).match(renameType(actuals[i].getType(), renamings, ctx.getCurrentAST().getLocation()), bindings);
         }
         
         if (!getReturnType().isBottom() && getReturnType().instantiate(bindings).isBottom()) {
diff --git a/src/org/rascalmpl/interpreter/result/RascalFunction.java b/src/org/rascalmpl/interpreter/result/RascalFunction.java
index 390142ec8e7..7eabbc774e7 100644
--- a/src/org/rascalmpl/interpreter/result/RascalFunction.java
+++ b/src/org/rascalmpl/interpreter/result/RascalFunction.java
@@ -128,7 +128,6 @@ private List<Statement> cloneBody() {
         return getAst().clone(body);
     }
 
-
     private String computeIndexedLabel(int pos, AbstractAST ast) {
         return ast.accept(new NullASTVisitor<String>() {
             @Override
diff --git a/src/org/rascalmpl/values/RascalFunctionValueFactory.java b/src/org/rascalmpl/values/RascalFunctionValueFactory.java
index 5f462421c07..9e496b66c46 100644
--- a/src/org/rascalmpl/values/RascalFunctionValueFactory.java
+++ b/src/org/rascalmpl/values/RascalFunctionValueFactory.java
@@ -304,6 +304,7 @@ public IFunction loadParsers(ISourceLocation saveLocation, IBool allowAmbiguity,
             tf.tupleType(rtf.reifiedType(parameterType), tf.valueType(), tf.sourceLocationType()), 
             tf.tupleEmpty());
 
+        @SuppressWarnings({"unchecked"})
         final Class<IGTD<IConstructor, ITree, ISourceLocation>> parser 
             = (Class<IGTD<IConstructor, ITree, ISourceLocation>>) ctx.getEvaluator()
                 .__getJavaBridge().loadClass(URIResolverRegistry.getInstance().getInputStream(saveLocation));
@@ -329,7 +330,7 @@ public IFunction loadParser(IValue reifiedGrammar, ISourceLocation saveLocation,
             tf.tupleType(tf.valueType(), tf.sourceLocationType()), 
             tf.tupleEmpty());
       
-
+        @SuppressWarnings({"unchecked"})
         final Class<IGTD<IConstructor, ITree, ISourceLocation>> parser 
             = (Class<IGTD<IConstructor, ITree, ISourceLocation>>) ctx.getEvaluator()
                 .__getJavaBridge().loadClass(URIResolverRegistry.getInstance().getInputStream(saveLocation));