diff --git a/deferred-folds.cabal b/deferred-folds.cabal
--- a/deferred-folds.cabal
+++ b/deferred-folds.cabal
@@ -1,7 +1,7 @@
 name:
   deferred-folds
 version:
-  0.6.6
+  0.6.7
 category:
   Folding
 synopsis:
diff --git a/library/DeferredFolds/UnfoldM.hs b/library/DeferredFolds/UnfoldM.hs
--- a/library/DeferredFolds/UnfoldM.hs
+++ b/library/DeferredFolds/UnfoldM.hs
@@ -68,6 +68,10 @@
 instance Show a => Show (UnfoldM Identity a) where
   show = show . toList
 
+{-# INLINE null #-}
+null :: Monad m => UnfoldM m input -> m Bool
+null (UnfoldM run) = run (\ _ _ -> return False) True
+
 {-| Perform a monadic strict left fold -}
 {-# INLINE foldlM' #-}
 foldlM' :: Monad m => (output -> input -> m output) -> output -> UnfoldM m input -> m output