diff --git a/indextype.cabal b/indextype.cabal
--- a/indextype.cabal
+++ b/indextype.cabal
@@ -1,5 +1,5 @@
 name:                 indextype
-version:              0.2.1.0
+version:              0.2.2.0
 synopsis: A series of type families and constraints for "indexable" types.
 description:
   This package deals with types that can roughly be "indexed" at compile time by an integer.
diff --git a/src/Control/IndexT/Constructor.hs b/src/Control/IndexT/Constructor.hs
--- a/src/Control/IndexT/Constructor.hs
+++ b/src/Control/IndexT/Constructor.hs
@@ -3,7 +3,6 @@
 {-# LANGUAGE KindSignatures #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE UndecidableInstances #-}
-{-# LANGUAGE PolyKinds #-}
 
 {-|
 This module provides a way to constrain types to be data constructors, much like
@@ -33,7 +32,7 @@
 
 the ith (zero based) parameter of the constructor with n parameters, i.e. @a_i@
 -}
-type family IndexC (n :: Nat) (i :: Nat) (a :: k1) = (r :: k2)
+type family IndexC (n :: Nat) (i :: Nat) a
 
 type instance IndexC 1 0 (_ a) = a
 type instance IndexC 2 0 (_ a _) = a