diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,7 @@
+2.0.5 [2022.05.07]
+------------------
+* Allow building with `transformers-0.6.*`.
+
 2.0.4 [2021.11.07]
 ------------------
 * Allow building with `template-haskell-2.18` (GHC 9.2).
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:       2.0.4
+version:       2.0.5
 license:       BSD3
 cabal-version: >= 1.10
 license-file:  LICENSE
@@ -85,12 +85,12 @@
     bytes            >= 0.15.2  && < 1,
     cereal           >= 0.4.1   && < 0.6,
     comonad          >= 5       && < 6,
-    hashable         >= 1.2.5.0 && < 1.4,
+    hashable         >= 1.2.5.0 && < 1.5,
     mmorph           >= 1.0     && < 1.3,
     deepseq          >= 1.4.2   && < 1.5,
     profunctors      >= 3.3     && < 6,
     th-abstraction   >= 0.4     && < 0.5,
-    transformers     >= 0.5     && < 0.6,
+    transformers     >= 0.5     && < 0.7,
     transformers-compat >= 0.5  && < 1
 
   ghc-options: -Wall -O2 -fspec-constr -fdicts-cheap -funbox-strict-fields
diff --git a/src/Bound/Class.hs b/src/Bound/Class.hs
--- a/src/Bound/Class.hs
+++ b/src/Bound/Class.hs
@@ -22,14 +22,16 @@
 
 import Control.Monad.Trans.Class
 import Control.Monad.Trans.Cont
-import Control.Monad.Trans.Error
 import Control.Monad.Trans.Identity
-import Control.Monad.Trans.List
 import Control.Monad.Trans.Maybe
 import Control.Monad.Trans.RWS
 import Control.Monad.Trans.Reader
 import Control.Monad.Trans.State
 import Control.Monad.Trans.Writer
+#if !(MIN_VERSION_transformers(0,6,0))
+import Control.Monad.Trans.Error
+import Control.Monad.Trans.List
+#endif
 
 infixl 1 >>>=
 
@@ -73,18 +75,10 @@
   m >>>= f = m >>= lift . f
   {-# INLINE (>>>=) #-}
 
-instance Error e => Bound (ErrorT e) where
- m >>>= f = m >>= lift . f
- {-# INLINE (>>>=) #-}
-
 instance Bound IdentityT where
  m >>>= f = m >>= lift . f
  {-# INLINE (>>>=) #-}
 
-instance Bound ListT where
- m >>>= f = m >>= lift . f
- {-# INLINE (>>>=) #-}
-
 instance Bound MaybeT where
  m >>>= f = m >>= lift . f
  {-# INLINE (>>>=) #-}
@@ -104,6 +98,16 @@
 instance Monoid w => Bound (WriterT w) where
  m >>>= f = m >>= lift . f
  {-# INLINE (>>>=) #-}
+
+#if !(MIN_VERSION_transformers(0,6,0))
+instance Error e => Bound (ErrorT e) where
+ m >>>= f = m >>= lift . f
+ {-# INLINE (>>>=) #-}
+
+instance Bound ListT where
+ m >>>= f = m >>= lift . f
+ {-# INLINE (>>>=) #-}
+#endif
 
 infixr 1 =<<<
 -- | A flipped version of ('>>>=').