diff --git a/src/org/rascalmpl/library/Type.rsc b/src/org/rascalmpl/library/Type.rsc
index 840e18dd60..3ccc265062 100644
--- a/src/org/rascalmpl/library/Type.rsc
+++ b/src/org/rascalmpl/library/Type.rsc
@@ -133,9 +133,9 @@ public Production choice(Symbol s, set[Production] choices) {
 	} else {   
 	    // TODO: this does not work in interpreter and typechecker crashes on it (both related to the splicing)
 	    //return choice(s, { *(choice(Symbol t, set[Production] b) := ch ? b : {ch}) | ch <- choices });
-	    changed = false;
-	    new_choices = {};
-        for (ch <- choices) {
+	    bool changed = false;
+	    set[Production] new_choices = {};
+         for (Production ch <- choices) {
             if (choice(Symbol _, set[Production] b) := ch) {
 	    		    changed = true;
 	    		    new_choices += b;