diff --git a/Control/Comonad/Trans/Store/Lazy.hs b/Control/Comonad/Trans/Store/Lazy.hs
--- a/Control/Comonad/Trans/Store/Lazy.hs
+++ b/Control/Comonad/Trans/Store/Lazy.hs
@@ -11,7 +11,7 @@
 -- The lazy store (state-in-context/costate) comonad transformer is subject to the laws:
 -- 
 -- > x = put (get x) x
--- > y = get (put y x)
+-- > y = get (put y) x)
 -- > put y x = put y (put z x)
 --
 -- Thanks go to Russell O'Connor and Daniel Peebles for their help formulating 
@@ -85,11 +85,11 @@
 get :: StoreT s w a -> s
 get (StoreT _ s) = s
 
-put :: Comonad w => s -> StoreT s w a -> a 
-put s ~(StoreT f _) = extract f s
+put :: Comonad w => s -> StoreT s w a -> StoreT s w a 
+put s ~(StoreT f _) = StoreT f s
 
-modify :: Comonad w => (s -> s) -> StoreT s w a -> a
-modify f ~(StoreT g s) = extract g (f s)
+modify :: Comonad w => (s -> s) -> StoreT s w a -> StoreT s w a
+modify f ~(StoreT g s) = StoreT g (f s)
 
 experiment :: (Comonad w, Functor f) => f (s -> s) -> StoreT s w a -> f a
 experiment fs ~(StoreT g s) = fmap (\f -> extract g (f s)) fs
diff --git a/Control/Comonad/Trans/Store/Memo.hs b/Control/Comonad/Trans/Store/Memo.hs
--- a/Control/Comonad/Trans/Store/Memo.hs
+++ b/Control/Comonad/Trans/Store/Memo.hs
@@ -93,11 +93,11 @@
 get :: StoreT s w a -> s
 get (StoreT _ s _) = s
 
-put :: Comonad w => s -> StoreT s w a -> a 
-put s (StoreT f _ _) = extract f s
+put :: Comonad w => s -> StoreT s w a -> StoreT s w a
+put s (StoreT f _ _) = storeT f s
 
-modify :: Comonad w => (s -> s) -> StoreT s w a -> a
-modify f (StoreT g s _) = extract g (f s)
+modify :: Comonad w => (s -> s) -> StoreT s w a -> StoreT s w a
+modify f (StoreT g s _) = storeT g (f s)
 
 experiment :: (Comonad w, Functor f) => f (s -> s) -> StoreT s w a -> f a
 experiment fs (StoreT g s _) = fmap (\f -> extract g (f s)) fs
diff --git a/Control/Comonad/Trans/Store/Strict.hs b/Control/Comonad/Trans/Store/Strict.hs
--- a/Control/Comonad/Trans/Store/Strict.hs
+++ b/Control/Comonad/Trans/Store/Strict.hs
@@ -85,11 +85,11 @@
 get :: StoreT s w a -> s
 get (StoreT _ s) = s
 
-put :: Comonad w => s -> StoreT s w a -> a 
-put s (StoreT f _) = extract f s
+put :: Comonad w => s -> StoreT s w a -> StoreT s w a
+put s (StoreT f _) = StoreT f s
 
-modify :: Comonad w => (s -> s) -> StoreT s w a -> a
-modify f (StoreT g s) = extract g (f s)
+modify :: Comonad w => (s -> s) -> StoreT s w a -> StoreT s w a
+modify f (StoreT g s) = StoreT g (f s)
 
 experiment :: (Comonad w, Functor f) => f (s -> s) -> StoreT s w a -> f a
 experiment fs (StoreT g s) = fmap (\f -> extract g (f s)) fs
diff --git a/comonad-transformers.cabal b/comonad-transformers.cabal
--- a/comonad-transformers.cabal
+++ b/comonad-transformers.cabal
@@ -1,6 +1,6 @@
 name:          comonad-transformers
 category:      Control, Comonads
-version:       1.3.0.1
+version:       1.4.0
 license:       BSD3
 cabal-version: >= 1.6
 license-file:  LICENSE