wget SSL certificate error on cygwin

$ wget -O - https://www.kernel.org
...
ERROR: The certificate of `www.kernel.org' is not trusted.
ERROR: The certificate of `www.kernel.org' hasn't got a known issuer.

$ apt-cyg install ca-certificates
$ cygcheck -l ca-certificates
/usr/ssl/certs/ca-bundle.crt
/usr/ssl/certs/ca-bundle.trust.crt
$ echo "ca_certificate = /usr/ssl/certs/ca-bundle.crt" >> /etc/wgetrc