diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,20 +1,31 @@
-0.1.1.1
--------
+Version 0.1.1.2
+===============
+
+<https://github.com/mstksg/prompt/releases/tag/v0.1.1.2>
+
+*   Reverted regression introduced in *v0.1.1.1* on versions of *transformers*
+    less than *0.5*.
+
+Version 0.1.1.1
+===============
+
 <https://github.com/mstksg/prompt/releases/tag/v0.1.1.1>
 
 *   Removed redundant `Error` constraint on `MonadPrompt` instance for
     `ErrorT`.
 
-0.1.1.0
--------
+Version 0.1.1.0
+===============
+
 <https://github.com/mstksg/prompt/releases/tag/v0.1.1.0>
 
 *   Fixed `Alternative` and `MonadPlus` instances to behave meaningfully ---
     that is, with "short circuiting" behavior for `t`'s that offer it.
 
 
-0.1.0.0
--------
+Version 0.1.0.0
+===============
+
 <https://github.com/mstksg/prompt/releases/tag/v0.1.0.0>
 
 *   Initial release!
diff --git a/prompt.cabal b/prompt.cabal
--- a/prompt.cabal
+++ b/prompt.cabal
@@ -2,7 +2,7 @@
 --  see http://haskell.org/cabal/users-guide/
 
 name:                prompt
-version:             0.1.1.1
+version:             0.1.1.2
 synopsis:            Monad (and transformer) for deferred-effect pure
                      prompt-response queries
 description:         Monad (and transformer) for delayed-effect "pure"
diff --git a/src/Control/Monad/Prompt/Class.hs b/src/Control/Monad/Prompt/Class.hs
--- a/src/Control/Monad/Prompt/Class.hs
+++ b/src/Control/Monad/Prompt/Class.hs
@@ -88,7 +88,11 @@
     prompt    = lift . prompt
     prompts f = lift . prompts f
 
+#if MIN_VERSION_transformers(0,5,0)
 instance (Monad m, MonadPrompt a b m) => MonadPrompt a b (ErrorT e m) where
+#else
+instance (Error e, Monad m, MonadPrompt a b m) => MonadPrompt a b (ErrorT e m) where
+#endif
     prompt    = lift . prompt
     prompts f = lift . prompts f
 
