diff --git a/src/Data/Store/Streaming.hs b/src/Data/Store/Streaming.hs
--- a/src/Data/Store/Streaming.hs
+++ b/src/Data/Store/Streaming.hs
@@ -86,7 +86,7 @@
 -- successfully deserialised object, or a request for more input.
 type PeekMessage i m a = FT ((->) i) m a
 
-needMoreInput :: Monad m => PeekMessage i m i
+needMoreInput :: PeekMessage i m i
 needMoreInput = wrap return
 {-# INLINE needMoreInput #-}
 
@@ -217,7 +217,7 @@
 {-# INLINE conduitEncode #-}
 
 -- | Conduit for decoding 'Message's from 'ByteString's.
-conduitDecode :: (MonadIO m, MonadResource m, Store a)
+conduitDecode :: (MonadResource m, Store a)
               => Maybe Int
               -- ^ Initial length of the 'ByteBuffer' used for
               -- buffering the incoming 'ByteString's.  If 'Nothing',
diff --git a/store.cabal b/store.cabal
--- a/store.cabal
+++ b/store.cabal
@@ -3,7 +3,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           store
-version:        0.4.1
+version:        0.4.2
 synopsis:       Fast binary serialization
 category:       Serialization, Data
 homepage:       https://github.com/fpco/store#readme
diff --git a/test/Data/StoreSpec.hs b/test/Data/StoreSpec.hs
--- a/test/Data/StoreSpec.hs
+++ b/test/Data/StoreSpec.hs
@@ -414,4 +414,4 @@
 
 isUnexpectedMarkerException :: Test.Hspec.Selector PeekException
 isUnexpectedMarkerException (PeekException _ t) =
-    "Expected marker: " `T.isPrefixOf` t
+    "Expected marker for ascending Map / IntMap: " `T.isPrefixOf` t