diff --git a/container.cabal b/container.cabal
--- a/container.cabal
+++ b/container.cabal
@@ -2,10 +2,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: ecc10876677b16d18a7273a11b6d2ca5c28c2e173d66b6bf5810c6434ac70f6c
+-- hash: eeed6fa2782121490ea5a84015d54a47965afd50cbd620616f3c4229d30e6ab2
 
 name:           container
-version:        1.1.0
+version:        1.1.1
 synopsis:       Containers abstraction and utilities.
 category:       Data
 stability:      experimental
@@ -34,7 +34,6 @@
       Data.Item
       Data.List.Class
       Data.Sequence.Class
-      Data.Set.Mutable.Class
   other-modules:
       Paths_container
   default-language: Haskell2010
diff --git a/src/Data/Set/Mutable/Class.hs b/src/Data/Set/Mutable/Class.hs
deleted file mode 100644
--- a/src/Data/Set/Mutable/Class.hs
+++ /dev/null
@@ -1,34 +0,0 @@
-module Data.Set.Mutable.Class 
-  (module Data.Set.Mutable.Class, module X) where
-
-import Prelude
-import Data.Item as X
-
-
-class Monad m => Set m s where
-    new        :: m s
-    singleton  :: Item s -> m s
-    insert     :: s ->  Item s  -> m () 
-    insertMany :: s -> [Item s] -> m ()
-    delete     :: s ->  Item s  -> m ()
-    member     :: s ->  Item s  -> m Bool
-    size       :: s -> m Int
-    null       :: s -> m Bool
-    toList     :: s -> m [Item s]
-    fromList   :: [Item s] -> m s
-
-    singleton el = do
-        s <- new
-        insert s el
-        pure s
-    {-# INLINE singleton #-}
-
-    insertMany s es = mapM_ (insert s) es ; {-# INLINE insertMany #-}
-
-    null = fmap (== 0) . size ; {-# INLINE null #-} 
-
-    fromList es = do
-        s <- new
-        insertMany s es
-        pure s
-    {-# INLINE fromList #-}