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diff --git a/testsuite/tests/mdo/should_fail/mdofail004.hs b/testsuite/tests/mdo/should_fail/mdofail004.hs
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+++ b/testsuite/tests/mdo/should_fail/mdofail004.hs
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+{-# OPTIONS -XRecursiveDo #-}
+
+-- OLD: mdo requires MonadFix instance, even
+--      if no recursion is present
+
+-- Dec 2010: Small change of behaviour
+--     MonadFix is only required if recursion is present
+
+module Main (main) where
+
+import Control.Monad.Fix
+
+data X a = X a deriving Show
+
+instance Monad X where
+  return      = X
+  (X a) >>= f = f a
+
+z :: X [Int]
+z = mdo { a <- return 1; return [a] }
+
+main = print z