diff --git a/monarch.cabal b/monarch.cabal
--- a/monarch.cabal
+++ b/monarch.cabal
@@ -1,5 +1,5 @@
 name:                monarch
-version:             0.9.0.0
+version:             0.10.0.0
 synopsis:            Monadic interface for TokyoTyrant.
 description:         This package provides simple monadic interface for TokyoTyrant.
 license:             BSD3
diff --git a/src/Database/Monarch/Types.hs b/src/Database/Monarch/Types.hs
--- a/src/Database/Monarch/Types.hs
+++ b/src/Database/Monarch/Types.hs
@@ -192,7 +192,7 @@
   return $ Connection sock
 
 -- | Monad Monarch interfaces
-class MonadMonarch m where
+class Monad m => MonadMonarch m where
 
   -- | Store a record.
   --   If a record with the same key exists in the database,
@@ -234,9 +234,7 @@
                 -> m ()
 
   -- | Remove a record.
-  out :: ( MonadBaseControl IO m
-         , MonadIO m ) =>
-         BS.ByteString -- ^ key
+  out :: BS.ByteString -- ^ key
       -> m ()
 
   -- | Remove records.