README.md in ssl_expiry-1.0.2 vs README.md in ssl_expiry-1.0.3

@@ -70,9 +70,17 @@
   ----------------------------------------------------------------------------------------------------
    antiphoton.com                 | expires on 09 Mar 2019 (in 16 days) [CN=antiphoton.com]
   ----------------------------------------------------------------------------------------------------
 ```
 
+### Custom port
+
+If you want to check an SSL expiry on a custom port you can do this by adding the port to the end of the domain.
+
+```
+  check-ssl -d antiphoton.com:8080
+```
+
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
 
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).