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: 60edf0481c7eca03c353b3f0926bb49816b6d3216abdc19c6ec063c7c4b88d00
+-- hash: 33bcc177224f7b11ee2bedc766f0da717dbbed2bf70e49e7b81beb1bcd4f755a
 
 name:           container
-version:        0.3.3
+version:        0.3.4
 synopsis:       Containers abstraction and utilities.
 category:       Data
 stability:      experimental
diff --git a/src/Data/Item.hs b/src/Data/Item.hs
--- a/src/Data/Item.hs
+++ b/src/Data/Item.hs
@@ -7,7 +7,9 @@
 import qualified Data.Text       as Strict
 import qualified Data.Text.Lazy  as Lazy
 
+import Data.Set (Set)
 
+
 type family Item a
 
 type instance Item [a] = a
@@ -15,3 +17,4 @@
 type instance Item (MapStrict.Map k v) = (k,v)
 type instance Item Strict.Text         = Char
 type instance Item Lazy.Text           = Char
+type instance Item (Set a)             = a