diff --git a/hedis-pile.cabal b/hedis-pile.cabal
--- a/hedis-pile.cabal
+++ b/hedis-pile.cabal
@@ -1,5 +1,5 @@
 name:           hedis-pile
-version:        0.5.0
+version:        0.5.1
 cabal-version:  >= 1.8
 build-type:     Simple
 stability:      Experimental
diff --git a/src/Database/Redis/Pile.hs b/src/Database/Redis/Pile.hs
--- a/src/Database/Redis/Pile.hs
+++ b/src/Database/Redis/Pile.hs
@@ -40,11 +40,14 @@
 --
 --   Time complexity depends on the situation. 
 --   
---   * @O(1)@ if data exists in cache and expect matches. 
+--   * @O(1)@ data exists in cache, expect matches. 
 --   
---   * @O(1)@ if data exists in cache and expect value is 'Nothing'.
+--   * @O(1)@ data exists in cache, expect value is 'Nothing'.
 --   
---   * @O(2)@
+--   * @O(2)@ data exists in cache, but expect value not matches value 
+--     in cache.
+--   
+--   * In all other cases time complexity does not make sense
 
 pile :: forall ma d . (MonadIO ma, ma ~ R.Redis, Binary d, Show d) => 
        B.ByteString