diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,7 @@
+1.0.4
+-----
+* Widened version bound on `transformers`.
+
 1.0.3
 -----
 * Added `bitransverseScope`.
diff --git a/bound.cabal b/bound.cabal
--- a/bound.cabal
+++ b/bound.cabal
@@ -1,6 +1,6 @@
 name:          bound
 category:      Language, Compilers/Interpreters
-version:       1.0.3
+version:       1.0.4
 license:       BSD3
 cabal-version: >= 1.9.2
 license-file:  LICENSE
@@ -75,7 +75,7 @@
     hashable-extras >= 0.1     && < 1,
     prelude-extras  >= 0.3     && < 1,
     profunctors     >= 3.3     && < 5,
-    transformers    >= 0.2     && < 0.4
+    transformers    >= 0.2     && < 0.5
 
   ghc-options: -Wall -O2 -fspec-constr -fdicts-cheap -funbox-strict-fields
 
@@ -86,7 +86,7 @@
   type: exitcode-stdio-1.0
   main-is: Simple.hs
   hs-source-dirs: examples
-  ghc-options -Wall -threaded
+  ghc-options: -Wall -threaded
   if impl(ghc<7.6.1)
     ghc-options: -Werror
   build-depends:
diff --git a/src/Bound/Scope/Simple.hs b/src/Bound/Scope/Simple.hs
--- a/src/Bound/Scope/Simple.hs
+++ b/src/Bound/Scope/Simple.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE Rank2Types #-}
 #if defined(__GLASGOW_HASKELL__)
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE StandaloneDeriving #-}
@@ -57,6 +58,10 @@
   , serializeScope
   , deserializeScope
   , hoistScope
+  , bitraverseScope
+  , bitransverseScope
+  , transverseScope
+  , instantiateVars
   ) where
 
 import Bound.Class
@@ -355,6 +360,28 @@
                  (b -> g d) -> (a -> g c) -> Scope b f a -> g (Scope d f c)
 traverseScope f g (Scope s) = Scope <$> traverse (bitraverse f g) s
 {-# INLINE traverseScope #-}
+
+-- | This allows you to 'bitraverse' a 'Scope'.
+bitraverseScope :: (Bitraversable t, Applicative f) => (k -> f k') -> (a -> f a') -> Scope b (t k) a -> f (Scope b (t k') a')
+bitraverseScope f = bitransverseScope (bitraverse f)
+{-# INLINE bitraverseScope #-}
+
+-- | This is a higher-order analogue of 'traverse'.
+transverseScope :: (Functor f)
+                => (forall r. g r -> f (h r))
+                -> Scope b g a -> f (Scope b h a)
+transverseScope tau (Scope s) = Scope <$> tau s
+
+-- | instantiate bound variables using a list of new variables
+instantiateVars :: Monad t => [a] -> Scope Int t a -> t a
+instantiateVars as = instantiate (vs !!) where
+  vs = map return as
+{-# INLINE instantiateVars #-}
+
+bitransverseScope :: Applicative f => (forall a a'. (a -> f a') ->         t a -> f         (u a'))
+                                   ->  forall a a'. (a -> f a') -> Scope b t a -> f (Scope b u a')
+bitransverseScope tau f (Scope s) = Scope <$> tau (traverse f) s
+{-# INLINE bitransverseScope #-}
 
 -- | mapM over both bound and free variables
 mapMBound :: (Monad m, Traversable f) =>