diff --git a/deque.cabal b/deque.cabal
--- a/deque.cabal
+++ b/deque.cabal
@@ -1,5 +1,5 @@
 name: deque
-version: 0.2.6
+version: 0.2.7
 synopsis: Double-ended queue
 description:
   An implementation of Double-Ended Queue (aka Dequeue or Deque)
diff --git a/library/Deque.hs b/library/Deque.hs
--- a/library/Deque.hs
+++ b/library/Deque.hs
@@ -131,6 +131,12 @@
   Deque consList snocList
 
 -- |
+-- /O(1)/. 
+null :: Deque a -> Bool
+null (Deque snocList consList) =
+  List.null snocList && List.null consList
+
+-- |
 -- /O(1)/, occasionally /O(n)/.
 head :: Deque a -> Maybe a
 head =