This guide is based on this excellent guide for El Capitan, but unlike that guide the following screenshots were taken on Yosemite.

  1. Download https://letsencrypt.org/certs/isrgrootx1.der to your desktop.

  2. Double-click the certificate to install it to your System Keychain.

  3. Follow the steps shown in the screenshots below.

screenshots

If you’ve found this guide so useful you want to give money, feel free to tip the author from which this guide was shamelessly ripped (because we thought some people using Yosemite would be tripped up by the original).

Last updated: 0001-01-01