diff --git a/examples/passing/UnknownInInstance.purs b/examples/passing/UnknownInInstance.purs
deleted file mode 100644
--- a/examples/passing/UnknownInInstance.purs
+++ /dev/null
@@ -1,8 +0,0 @@
-module Main where
-
-data Proxy a = Proxy
-
-test :: forall a. (Show (Proxy a)) => String
-test = show Proxy
-
-main = Debug.Trace.trace "Done"
diff --git a/purescript.cabal b/purescript.cabal
--- a/purescript.cabal
+++ b/purescript.cabal
@@ -1,5 +1,5 @@
 name: purescript
-version: 0.6.7
+version: 0.6.7.1
 cabal-version: >=1.8
 build-type: Simple
 license: MIT
diff --git a/src/Language/PureScript/TypeChecker/Entailment.hs b/src/Language/PureScript/TypeChecker/Entailment.hs
--- a/src/Language/PureScript/TypeChecker/Entailment.hs
+++ b/src/Language/PureScript/TypeChecker/Entailment.hs
@@ -202,9 +202,6 @@
 typeHeadsAreEqual :: ModuleName -> Environment -> Type -> Type -> Maybe [(String, Type)]
 typeHeadsAreEqual _ _ (Skolem _ s1 _)      (Skolem _ s2 _)      | s1 == s2 = Just []
 typeHeadsAreEqual _ _ t                    (TypeVar v)                     = Just [(v, t)]
--- In this case, we might want type information to flow back to the typechecker.
--- TODO: run this function in the UnifyT monad.
-typeHeadsAreEqual _ _ (TUnknown _)         _                    = Just []
 typeHeadsAreEqual _ _ (TypeConstructor c1) (TypeConstructor c2) | c1 == c2 = Just []
 typeHeadsAreEqual m e (TypeApp h1 t1)      (TypeApp h2 t2)                 = (++) <$> typeHeadsAreEqual m e h1 h2 
                                                                                   <*> typeHeadsAreEqual m e t1 t2