diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+1.1.1
+
+* Increase upper bound on `transformers-compat`
+
 1.1.0
 
 * BREAKING CHANGE: Enable `PolyKinds`
diff --git a/mmorph.cabal b/mmorph.cabal
--- a/mmorph.cabal
+++ b/mmorph.cabal
@@ -1,5 +1,5 @@
 Name: mmorph
-Version: 1.1.0
+Version: 1.1.1
 Cabal-Version: >= 1.8.0.2
 Build-Type: Simple
 License: BSD3
@@ -23,6 +23,6 @@
         base                >= 4       && < 5  ,
         mtl                 >= 2.1     && < 2.3,
         transformers        >= 0.2.0.0 && < 0.6,
-        transformers-compat >= 0.3     && < 0.6
+        transformers-compat >= 0.3     && < 0.7
     Exposed-Modules: Control.Monad.Morph, Control.Monad.Trans.Compose
     GHC-Options: -O2
diff --git a/src/Control/Monad/Morph.hs b/src/Control/Monad/Morph.hs
--- a/src/Control/Monad/Morph.hs
+++ b/src/Control/Monad/Morph.hs
@@ -106,6 +106,9 @@
 class MFunctor t where
     {-| Lift a monad morphism from @m@ to @n@ into a monad morphism from
         @(t m)@ to @(t n)@
+
+        The first argument to `hoist` must be a monad morphism, even though the
+        type system does not enforce this
     -}
     hoist :: (Monad m) => (forall a . m a -> n a) -> t m b -> t n b