Typechecking error: "Could not deduce (m ~ m1)..."

This program:

import Control.Monad

f x = let
  g y = let
    h z = liftM not x
    in h 0
  in g 0

is expected to compile. Instead, it produces an error:

test.hs:5:21:
    Could not deduce (m ~ m1)
    from the context (Monad m)
      bound by the inferred type of f :: Monad m => m Bool -> m Bool
      at test.hs:(3,1)-(7,8)
    or from (m Bool ~ m1 Bool, Monad m1)
      bound by the inferred type of
               h :: (m Bool ~ m1 Bool, Monad m1) => t1 -> m1 Bool
      at test.hs:5:5-21
      `m' is a rigid type variable bound by
          the inferred type of f :: Monad m => m Bool -> m Bool
          at test.hs:3:1
      `m1' is a rigid type variable bound by
           the inferred type of
           h :: (m Bool ~ m1 Bool, Monad m1) => t1 -> m1 Bool
           at test.hs:5:5
    Expected type: m1 Bool
      Actual type: m Bool
    In the second argument of `liftM', namely `x'
    In the expression: liftM not x
    In an equation for `h': h z = liftM not x

Trac metadata

Trac field	Value
Version	7.6.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
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