Adding Skype social icon

I have added Skype to the Social Links – but want to be able to add a Skype format URL to the URL field – of this kind: skype:name?call – where name is the name of the recipient of the Skype call.

As it stands the URL entered isn’t registered – presumably because the URL is non-standard – as suggested by this warning under the box for the URL: “Enter the full url of your social profile (must be a valid url).” Is there a way of amending the theme to allow Skype format URLs when the Skype icon is selected from the drop-down list?