Social share links broken

Hi !
First of all, the plugin is great, it helped me a lot.
However, I still have an issue with the social share links that I got in my theme.
I have something like this in my single.php file :
<a id="facebook" href="http://www.facebook.com/sharer.php?u=<?php echo urlencode(get_permalink()); ?>" target="_blank">Facebook</a>
When you click on it, it redirects you to : https://www.facebook.com/sharer.php?u=//mywebsite.com
Instead of : https://www.facebook.com/sharer.php?u=https://mywebsite.com

I have the exact same problem with Twitter.
Can you help me ?
Thanks !