tw.get_access_token not working

[gorodscy]

Calling this method gives me back an error:

OAuth2::Error - unauthorized: Full authentication is required to access this resource
{"error":"unauthorized","error_description":"Full authentication is required to access this resource"}

I'm using it like described in the README:

tw = TransferWise::OAuth.new(transferwise_client_id, transferwise_client_secret)

...
# got the code PS: I made sure I'm using the same redirect_url
...

token = tw.get_access_token(code, transferwise_redirect_url)

Please let me know if there's any other information you need.