diff --git a/util/collection/KList.scala b/util/collection/KList.scala
index 7b58aca32..5c0952cf1 100644
--- a/util/collection/KList.scala
+++ b/util/collection/KList.scala
@@ -13,7 +13,7 @@ import Types._
 * For background, see
 * http://apocalisp.wordpress.com/2010/11/01/type-level-programming-in-scala-part-8a-klist%C2%A0motivation/
  */
-sealed trait KList[+M[_], HL <: HList]
+sealed trait KList[M[_], HL <: HList]
 {
 	type Raw = HL
 	/** Transform to the underlying HList type.*/
@@ -33,12 +33,12 @@ trait KFold[M[_],P[_ <: HList]]
 	def knil: P[HNil]
 }
 
-final case class KCons[H, T <: HList, +M[_]](head: M[H], tail: KList[M,T]) extends KList[M, H :+: T]
+final case class KCons[H, T <: HList, M[_]](head: M[H], tail: KList[M,T]) extends KList[M, H :+: T]
 {
 	def down(implicit f: M ~> Id) = HCons(f(head), tail down f)
 	def transform[N[_]](f: M ~> N) = KCons( f(head), tail transform f )
 	// prepend
-	def :^: [N[X] >: M[X], G](g: N[G]) = KCons(g, this)
+	def :^: [G](g: M[G]) = KCons(g, this)
 	def toList = head :: tail.toList
 	
 	def combine[N[X] >: M[X]]: (H :+: T)#Wrap[N] = HCons(head, tail.combine)
@@ -48,29 +48,31 @@ final case class KCons[H, T <: HList, +M[_]](head: M[H], tail: KList[M,T]) exten
 	def foldr[P[_ <: HList],N[X] >: M[X]](f: KFold[N,P]) = f.kcons(head, tail foldr f)
 }
 
-sealed class KNil extends KList[Nothing, HNil]
+sealed case class KNil[M[_]]() extends KList[M, HNil]
 {
-	def down(implicit f: Nothing ~> Id) = HNil
-	def transform[N[_]](f: Nothing ~> N) = KNil
-	def :^: [M[_], H](h: M[H]) = KCons(h, this)
+	def down(implicit f: M ~> Id) = HNil
+	def transform[N[_]](f: M ~> N) = new KNil[N]
 	def toList = Nil
 	def combine[N[X]] = HNil
 	override def foldr[P[_ <: HList],N[_]](f: KFold[N,P]) = f.knil
 	override def toString = "KNil"
 }
-object KNil extends KNil
-
+object KNil
+{
+	def :^: [M[_], H](h: M[H]) = KCons(h, new KNil[M])
+}
 object KList
 {
+	implicit def convert[M[_]](k: KNil.type): KNil[M] = KNil()
 	// nicer alias for pattern matching
 	val :^: = KCons
 	
-	def fromList[M[_]](s: Seq[M[_]]): KList[M, _ <: HList] = if(s.isEmpty) KNil else KCons(s.head, fromList(s.tail))
+	def fromList[M[_]](s: Seq[M[_]]): KList[M, _ <: HList] = if(s.isEmpty) KNil() else KCons(s.head, fromList(s.tail))
 
 	// haven't found a way to convince scalac that KList[M, H :+: T] implies KCons[H,T,M]
 	// Therefore, this method exists to put the cast in one location.
 	implicit def kcons[H, T <: HList, M[_]](kl: KList[M, H :+: T]): KCons[H,T,M] =
 		kl.asInstanceOf[KCons[H,T,M]]
 	// haven't need this, but for symmetry with kcons:
-	implicit def knil[M[_]](kl: KList[M, HNil]): KNil = KNil
+	implicit def knil[M[_]](kl: KList[M, HNil]): KNil[M] = KNil()
 }
diff --git a/util/collection/Types.scala b/util/collection/Types.scala
index 42b81f990..3a4be2c11 100644
--- a/util/collection/Types.scala
+++ b/util/collection/Types.scala
@@ -7,7 +7,7 @@ object Types extends Types
 {
 	implicit def hconsToK[M[_], H, T <: HList](h: M[H] :+: T)(implicit mt: T => KList[M, T]): KList[M, H :+: T] =
 		KCons[H, T, M](h.head, mt(h.tail) )
-	implicit def hnilToK(hnil: HNil): KNil = KNil
+	implicit def hnilToK[M[_]](hnil: HNil): KNil[M] = KNil()
 }
 
 trait Types extends TypeFunctions