Pipenv on Windows: 'module' object is not callable

I'm having trouble using Pipenv on my Windows 10 machine. Initially, I got a timeout error while trying to run pipenv install <module> and following this answer, I disabled Windows Defender.

That got rid of the timeout error and it then seems to successfully install the package at ~/.virtualenvs but I get an error when it comes to creating Pipfile.lock:

Adding flask to Pipfile's [packages]...
Pipfile.lock not found, creating...
Locking [dev-packages] dependencies...
Locking [packages] dependencies...
File "C:\Users\Edgar\AppData\Roaming\Python\Python36\site-packages\pipenv\utils.py", line 402, in resolve_deps
    req_dir=req_dir
File "C:\Users\Edgar\AppData\Roaming\Python\Python36\site-packages\pipenv\utils.py", line 250, in actually_resolve_deps
    req = Requirement.from_line(dep)
File "C:\Users\Edgar\AppData\Roaming\Python\Python36\site-packages\pipenv\vendor\requirementslib\models\requirements.py", line 704, in from_line
    line, extras = _strip_extras(line)
TypeError: 'module' object is not callable

I've tried installing requests and flask, with the same results.

• python: Python 3.6.4 :: Anaconda, Inc.
• pip: pip 18.0 from c:\users\edgar\anaconda3\lib\site-packages\pip (python 3.6)
• pipenv: pipenv, version 2018.7.1

Any clues as to what is the problem/solution?

Finally solved it. This is current issue, with a workaround for Windows:

pipenv run python -m pip install -U pip==18.0