diff --git a/src/Control.Monad.State.Async.purs b/src/Control.Monad.State.Async.purs
index 0e2341c..6488e16 100644
--- a/src/Control.Monad.State.Async.purs
+++ b/src/Control.Monad.State.Async.purs
@@ -10,6 +10,7 @@ import Control.Monad.Reader (class MonadAsk, ReaderT(..), ask)
 import Control.Monad.Rec.Class (class MonadRec)
 import Control.Monad.Trans.Class (class MonadTrans, lift)
 import Control.Monad.Unlift (class MonadUnlift)
+import Control.MonadPlus (class MonadPlus)
 import Control.Parallel (class Parallel, parallel, sequential)
 import Data.Async.Class (class AsyncState)
 import Data.Async.Class as State
@@ -266,6 +267,7 @@ newtype AsyncStateT w s m ma = AsyncStateT (ReaderT (w s) m ma)
 
 derive instance Newtype (AsyncStateT w s m ma) _
 derive newtype instance MonadTrans (AsyncStateT w s)
+derive newtype instance (MonadPlus m) => MonadPlus (AsyncStateT w s m)
 derive newtype instance (Alternative m) => Alternative (AsyncStateT w s m)
 derive newtype instance (Alt m) => Alt (AsyncStateT w s m)
 derive newtype instance (Plus m) => Plus (AsyncStateT w s m)