diff --git a/testcases/verification/graph/SortedNDList.scala b/testcases/verification/graph/SortedNDList.scala
index 42a16cfbd8cdea49a1c5c8a17e61d8dab052dc67..a6f5e11635dd3e9dc955f78e814b2dfc86d6aaac 100644
--- a/testcases/verification/graph/SortedNDList.scala
+++ b/testcases/verification/graph/SortedNDList.scala
@@ -10,7 +10,7 @@ object SortedNDList {
    * values must be unique and non-negative.
    */
   abstract class SortedNDList
-  case class ListNode(val node : Int, val dist : Int, var next : SortedNDList) extends SortedNDList
+  case class ListNode(node: Int, dist: Int, next: SortedNDList) extends SortedNDList
   case class ListEnd() extends SortedNDList
   
   /** List invariant (see description above) */
diff --git a/testcases/verification/graph/dijkstras/DijkstrasSortedList.scala b/testcases/verification/graph/dijkstras/DijkstrasSortedList.scala
index 20461a2566544e3c61e7d3c5a59f1483651f6d3e..4ac5d863e880a484a00a8fef939964607320e6db 100644
--- a/testcases/verification/graph/dijkstras/DijkstrasSortedList.scala
+++ b/testcases/verification/graph/dijkstras/DijkstrasSortedList.scala
@@ -74,7 +74,7 @@ object DijkstrasSortedList {
    * values must be unique and non-negative.
    */
   abstract class SortedNDList
-  case class ListNode(val node : Int, val dist : Int, var next : SortedNDList) extends SortedNDList
+  case class ListNode(node : Int, dist : Int, next : SortedNDList) extends SortedNDList
   case class ListEnd() extends SortedNDList
   
   /** List invariant (see description above) */