diff --git a/Codec/Binary/Base91/Control.hs b/Codec/Binary/Base91/Control.hs
new file mode 100644
--- /dev/null
+++ b/Codec/Binary/Base91/Control.hs
@@ -0,0 +1,29 @@
+-- Copyright 2015 Alvaro J. Genial (http://alva.ro) -- see LICENSE.md for more.
+
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE UndecidableInstances #-}
+
+module Codec.Binary.Base91.Control (Applicative' (..), Foldable' (..)) where
+
+import Control.Applicative (Applicative, pure)
+import Data.Foldable (Foldable, foldl')
+import Data.Monoid (Monoid)
+
+-- A version of 'Applicative' compatible with monomorphic containers.
+class (Monoid a) => Applicative' a where
+    type Item a :: *
+    pure' :: Item a -> a
+
+instance (Applicative a, Monoid (a i)) => Applicative' (a i) where
+  type Item (a i) = i
+  pure' = pure
+
+-- A version of 'Foldable' compatible with monomorphic containers.
+class Foldable' f where
+    type Element f :: *
+    fold' :: (x -> Element f -> x) -> x -> f -> x
+
+instance (Foldable f) => Foldable' (f e) where
+  type Element (f e) = e
+  fold' = foldl'
diff --git a/base91.cabal b/base91.cabal
--- a/base91.cabal
+++ b/base91.cabal
@@ -1,5 +1,5 @@
 Name:                  base91
-Version:               1.0.0
+Version:               1.0.1
 Author:                Alvaro J. Genial
 Maintainer:            ajg
 Homepage:              https://github.com/ajg/base91
@@ -24,7 +24,7 @@
 
 Library
   Build-Depends:       base >= 4 && < 5
-  Exposed-Modules:     Codec.Binary.Base91, Codec.Binary.Base91.String
+  Exposed-Modules:     Codec.Binary.Base91, Codec.Binary.Base91.Control, Codec.Binary.Base91.String
 
   if flag(ByteString)
     Build-Depends:     bytestring