diff --git a/monadplus.cabal b/monadplus.cabal
--- a/monadplus.cabal
+++ b/monadplus.cabal
@@ -1,6 +1,6 @@
 
 name:               monadplus
-version:            1.4
+version:            1.4.1
 cabal-version:      >= 1.10
 author:             Hans Hoglund
 maintainer:         Hans Hoglund <hans@hanshoglund.se>
diff --git a/src/Control/Monad/Plus.hs b/src/Control/Monad/Plus.hs
--- a/src/Control/Monad/Plus.hs
+++ b/src/Control/Monad/Plus.hs
@@ -1,8 +1,5 @@
 
-{-# LANGUAGE DeriveFunctor, DeriveFoldable, GeneralizedNewtypeDeriving,
-
-    TypeSynonymInstances
-    #-}
+{-# LANGUAGE DeriveFunctor, DeriveFoldable, GeneralizedNewtypeDeriving #-}
 
 -------------------------------------------------------------------------------------
 -- |
@@ -229,7 +226,10 @@
 
 instance Monad (Partial r) where
     return x = Partial (\_ -> Just x)
-    Partial f >>= k = Partial $ \r -> f r >>= \x -> getPartial (k x) r
+    Partial f >>= k = Partial $ \r -> do { x <- f r; getPartial (k x) r }
+    -- f >>= k = (join' . fmap k) f
+        -- where
+            -- join' g = Partial $ \x -> do { h <- getPartial g x; getPartial h x }
 
 instance MonadPlus (Partial r) where
     mzero = Partial (const Nothing)