Index: src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-svg-icons.php
===================================================================
--- src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-svg-icons.php	(revision 54948)
+++ src/wp-content/themes/twentytwentyone/classes/class-twenty-twenty-one-svg-icons.php	(working copy)
@@ -127,6 +127,43 @@
 		'mail'      => array(
 			'mailto:',
 		),
+		'mastodon'  => array(
+			'mastodon.social',
+			'pawoo.net',
+			'mstdn.jp',
+			'mastodon.cloud',
+			'mastodon.online',
+			'counter.social',
+			'mstdn.social',
+			'mas.to',
+			'mastodon.world',
+			'gc2.jp',
+			'mastodon.lol',
+			'pixelfed.social',
+			'mastodon.sdf.org',
+			'c.im',
+			'mastodonapp.uk',
+			'universeodon.com',
+			'mastodon.uno',
+			'masto.ai',
+			'techhub.social',
+			'fosstodon.org',
+			'brighteon.social',
+			'mastodon.top',
+			'mstdn.party',
+			'mamot.fr',
+			'infosec.exchange',
+			'm.cmx.im',
+			'ohai.social',
+			'sfba.social',
+			'troet.cafe',
+			'mastodon.poppingboxes.org',
+			'hachyderm.io',
+			'alive.bar',
+			'home.social',
+			'kolektiva.social',
+			'masthead.social',
+		),
 		'pocket'    => array(
 			'getpocket.com',
 		),