diff --git a/Data/Conduit/Base64.hs b/Data/Conduit/Base64.hs
--- a/Data/Conduit/Base64.hs
+++ b/Data/Conduit/Base64.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE RankNTypes #-}
+
 module Data.Conduit.Base64
     ( encode
     , decode
diff --git a/base64-conduit.cabal b/base64-conduit.cabal
--- a/base64-conduit.cabal
+++ b/base64-conduit.cabal
@@ -1,5 +1,5 @@
 Name:                base64-conduit
-Version:             0.5.0
+Version:             0.5.1
 Synopsis:            Base64-encode and decode streams of bytes.
 Description:         Base64-encode and decode streams of bytes.
 License:             BSD3