AttributeError: module 'libnacl' has no attribute '__version__'

#!/usr/bin/env python3
from sys import argv
from duniterpy.key import SigningKey

# path to save to
path = "/tmp/secret.dunikey"

key = SigningKey.from_credentials(argv[1], argv[2], None)
key.save_pubsec_file(path)
print(
    key.pubkey,
)

Traceback (most recent call last):
  File "dunikey.py", line 3, in <module>
    from duniterpy.key import SigningKey
  File "/home/pi/.local/lib/python3.7/site-packages/duniterpy/__init__.py", line 22, in <module>
    from . import api, documents, key
  File "/home/pi/.local/lib/python3.7/site-packages/duniterpy/key/__init__.py", line 21, in <module>
    from .ascii_armor import AsciiArmor
  File "/home/pi/.local/lib/python3.7/site-packages/duniterpy/key/ascii_armor.py", line 34, in <module>
    VERSION_FIELD_VALUE = "Python Libnacl " + libnacl.__version__
AttributeError: module 'libnacl' has no attribute '__version__'