diff --git a/app/lib/ostatus/activity/creation.rb b/app/lib/ostatus/activity/creation.rb
index cede5750..2b258afe 100644
--- a/app/lib/ostatus/activity/creation.rb
+++ b/app/lib/ostatus/activity/creation.rb
@@ -90,7 +90,7 @@ class OStatus::Activity::Creation < OStatus::Activity::Base
   end
 
   def visibility_scope
-    @xml.at_xpath('./gabsocial:scope', gabsocial: OStatus::TagManager::MTDN_XMLNS)&.content&.to_sym || :public
+    @xml.at_xpath('./mastodon:scope', mastodon: OStatus::TagManager::MTDN_XMLNS)&.content&.to_sym || :public
   end
 
   def published
diff --git a/app/lib/ostatus/atom_serializer.rb b/app/lib/ostatus/atom_serializer.rb
index 1967dcb1..17115444 100644
--- a/app/lib/ostatus/atom_serializer.rb
+++ b/app/lib/ostatus/atom_serializer.rb
@@ -32,7 +32,7 @@ class OStatus::AtomSerializer
     append_element(author, 'poco:preferredUsername', account.username)
     append_element(author, 'poco:displayName', account.display_name) if account.display_name?
     append_element(author, 'poco:note', account.local? ? account.note : strip_tags(account.note)) if account.note?
-    append_element(author, 'gabsocial:scope', account.locked? ? :private : :public)
+    append_element(author, 'mastodon:scope', account.locked? ? :private : :public)
 
     author
   end
@@ -345,7 +345,7 @@ class OStatus::AtomSerializer
     parent['xmlns:poco']     = OStatus::TagManager::POCO_XMLNS
     parent['xmlns:media']    = OStatus::TagManager::MEDIA_XMLNS
     parent['xmlns:ostatus']  = OStatus::TagManager::OS_XMLNS
-    parent['xmlns:gabsocial'] = OStatus::TagManager::MTDN_XMLNS
+    parent['xmlns:mastodon'] = OStatus::TagManager::MTDN_XMLNS
   end
 
   def serialize_status_attributes(entry, status)
@@ -369,7 +369,7 @@ class OStatus::AtomSerializer
     end
 
     append_element(entry, 'category', nil, term: 'nsfw') if status.sensitive? && status.media_attachments.any?
-    append_element(entry, 'gabsocial:scope', status.visibility)
+    append_element(entry, 'mastodon:scope', status.visibility)
 
     status.emojis.each do |emoji|
       append_element(entry, 'link', nil, rel: :emoji, href: full_asset_url(emoji.image.url), name: emoji.shortcode)