diff --git a/src/funcheck/scalacheck/ScalaCheck.scala b/src/funcheck/scalacheck/ScalaCheck.scala
index fac7ef110098858c8f6cf14aefe220c95bc32e91..b1304476c42f32fed2f9eda7ecd8d99aa2dba26b 100644
--- a/src/funcheck/scalacheck/ScalaCheck.scala
+++ b/src/funcheck/scalacheck/ScalaCheck.scala
@@ -334,12 +334,12 @@ trait ScalaCheck extends FreshNameCreator {
     tpe2arbApp += StringClass.typeConstructor    -> arbString
     tpe2arbApp += OptionClass.typeConstructor    -> arbOption
     
-    lazy val ImmutableMapClass: Symbol = definitions.getClass(newTypeName("scala.collection.immutable.Map"))
-    lazy val ImmutableSetClass: Symbol = definitions.getClass(newTypeName("scala.collection.immutable.Set"))
+    //lazy val ImmutableMapClass: Symbol = definitions.getClass(newTypeName("scala.collection.immutable.Map"))
+    //lazy val ImmutableSetClass: Symbol = definitions.getClass(newTypeName("scala.collection.immutable.Set"))
     
-    tpe2arbApp += ImmutableMapClass.typeConstructor    -> arbImmutableMap
+    //tpe2arbApp += ImmutableMapClass.typeConstructor    -> arbImmutableMap
     tpe2arbApp += ListClass.typeConstructor            -> arbList
-    tpe2arbApp += ImmutableSetClass.typeConstructor    -> arbSet
+    //tpe2arbApp += ImmutableSetClass.typeConstructor    -> arbSet
     tpe2arbApp += TupleClass(2).typeConstructor        -> arbTuple2 
     
     /**