diff --git a/Network/Wai/Session/Map.hs b/Network/Wai/Session/Map.hs
--- a/Network/Wai/Session/Map.hs
+++ b/Network/Wai/Session/Map.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE CPP #-}
+{-# LANGUAGE CPP, FlexibleContexts #-}
 module Network.Wai.Session.Map (mapStore, mapStore_) where
 
 import Control.Monad
diff --git a/wai-session.cabal b/wai-session.cabal
--- a/wai-session.cabal
+++ b/wai-session.cabal
@@ -1,5 +1,5 @@
 name:            wai-session
-version:         0.3.1
+version:         0.3.2
 cabal-version:   >= 1.8
 license:         OtherLicense
 license-file:    COPYING