closure factory proc

[GillesRamstein]

I have this nim code in factory.nim

proc factory*(): proc(x: int) {.exportpy.} =
  var state: int = 1
  proc inner(x: int) =
    state = state + x
    echo state
  return inner


when isMainModule:
  let innerProc = factory()
  innerProc(2)
  innerProc(3)

Without the {.exportpy.} it compiles and runs just fine.
With the {.exportpy.} pragma i get following error message:

stack trace: (most recent call last)
/home/gilles/.nimble/pkgs2/nimpy-0.2.0-fb4ac75c25a76340c14a0d45b356c4598e03aea6/nimpy.nim(797, 24) exportpy
/nix/store/vih5nywn3j2s95lnma0wjbx61q0k1wz5-nim-unwrapped-2.0.2/nim/lib/core/macros.nim(1307, 12) name
/nix/store/vih5nywn3j2s95lnma0wjbx61q0k1wz5-nim-unwrapped-2.0.2/nim/lib/core/macros.nim(1219, 27) expectKind
/home/gilles/code/pynf/indicators/nim/indicators.nim(50, 22) Error: Expected one of {nnkLambda, nnkDo, nnkProcDef, nnkMethodDef, nnkConverterDef, nnkMacroDef, nnkTemplateDef, nnkIteratorDef, nnkFuncDef}, got nnkProcTy

Is this supposed to work or a known limitation?
Or is there another way i could implement this kind of factory proc which is compatible with nimporter?
Thanks in advance for any insights!

Edit: code highlighting

[GillesRamstein]

proc factory*(): (proc(x: int)) {.exportpy.} =
  var state: int = 1
  proc inner(x: int) =
    state = state + x
    echo state
  return inner


when isMainModule:
  let innerProc = factory()
  innerProc(2)
  innerProc(3)

Adding parenthesis around the return type did the trick.