Don't match type level arithmetic result with same literal value on GHC 7.6.1

gistfile1.hs

-- $ ghci
-- GHCi, version 7.6.1: http://www.haskell.org/ghc/  :? for help
ghci> import GHC.TypeLits
ghci> :set -XDataKinds 
ghci> :set -XPolyKinds 
ghci> :set -XGADTs 
ghci> data EqRefl a b where { Refl :: EqRefl a a }

ghci> :t Refl :: EqRefl 1 1
Refl :: EqRefl 1 1 :: EqRefl Nat 1 1

ghci> :set -XTypeOperators 
ghci> :t Refl :: EqRefl 1 (0 + 1)
<interactive>:1:1:
    Couldn't match type `0 + 1' with `1'
    Expected type: EqRefl Nat 1 (0 + 1)
      Actual type: EqRefl Nat 1 1
    In the expression: Refl :: EqRefl 1 (0 + 1)