diff --git a/monad-skeleton.cabal b/monad-skeleton.cabal
--- a/monad-skeleton.cabal
+++ b/monad-skeleton.cabal
@@ -1,5 +1,5 @@
 name:                monad-skeleton
-version:             0.1.3
+version:             0.1.3.1
 synopsis:            Monads of program skeleta
 description:         Fast operational monad library
 homepage:            https://github.com/fumieval/monad-skeleton
diff --git a/src/Control/Monad/Zombie.hs b/src/Control/Monad/Zombie.hs
--- a/src/Control/Monad/Zombie.hs
+++ b/src/Control/Monad/Zombie.hs
@@ -26,6 +26,10 @@
   return a = Zombie [Spine (Return a) id]
   Zombie xs >>= k = Zombie $ map (graftSpine $ Leaf $ Kleisli k) xs
 
+instance MonadPlus (Zombie t) where
+  mzero = empty
+  mplus = (<|>)
+
 -- | Turn a decomposed form into a composed form.
 embalm :: MonadView t (Zombie t) a -> Zombie t a
 embalm t = Zombie [Spine t id]