wkhtmltopdf UnicodeDecodeError: 'utf-8' codec can't decode byte 0x90 in position 4: invalid start byte

При запуске кода (библиотека pdfkit + wkhtmltopdf) получаю ошибку UnicodeDecodeError: 'utf-8' codec can't decode byte 0x90 in position 4: invalid start byte. Запускается под windows 10, python3. Код и стектрейс ниже. Чем лечится?

Код:

import pdfkit

options = {
    'quiet': ''
}
a = '1'
pdfkit.from_string(a, 'report1.pdf', options=options)

Traceback:

Traceback (most recent call last):
  File "script.py", line 43, in <module>
    pdfkit.from_string(a, 'report1.pdf', options=options)
  File "C:\Users\user\AppData\Local\Programs\Python\Python37\lib\site-packages\pdfkit\api.py", line 70, in from_string
    configuration=configuration, cover_first=cover_first)
  File "C:\Users\user\AppData\Local\Programs\Python\Python37\lib\site-packages\pdfkit\pdfkit.py", line 42, in __init__
    self.configuration = (Configuration() if configuration is None
  File "C:\Users\user\AppData\Local\Programs\Python\Python37\lib\site-packages\pdfkit\configuration.py", line 21, in __init__
    with open(self.wkhtmltopdf) as f:
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x90 in position 4: invalid start byte