diff --git a/app/lib/ostatus/activity/creation.rb b/app/lib/ostatus/activity/creation.rb
index 81607950..cede5750 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::GABSCL_XMLNS)&.content&.to_sym || :public
+    @xml.at_xpath('./gabsocial:scope', gabsocial: 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 348f7601..1967dcb1 100644
--- a/app/lib/ostatus/atom_serializer.rb
+++ b/app/lib/ostatus/atom_serializer.rb
@@ -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::GABSCL_XMLNS
+    parent['xmlns:gabsocial'] = OStatus::TagManager::MTDN_XMLNS
   end
 
   def serialize_status_attributes(entry, status)
diff --git a/app/lib/ostatus/tag_manager.rb b/app/lib/ostatus/tag_manager.rb
index 20d75645..e04b4144 100644
--- a/app/lib/ostatus/tag_manager.rb
+++ b/app/lib/ostatus/tag_manager.rb
@@ -15,8 +15,8 @@ class OStatus::TagManager
     authorize:      'http://activitystrea.ms/schema/1.0/authorize',
     reject:         'http://activitystrea.ms/schema/1.0/reject',
     unfollow:       'http://ostatus.org/schema/1.0/unfollow',
-    block:          'http://gab.com/schema/1.0/block',
-    unblock:        'http://gab.com/schema/1.0/unblock',
+    block:          'http://mastodon.social/schema/1.0/block',
+    unblock:        'http://mastodon.social/schema/1.0/unblock',
   }.freeze
 
   TYPES = {
@@ -39,7 +39,7 @@ class OStatus::TagManager
   POCO_XMLNS   = 'http://portablecontacts.net/spec/1.0'
   DFRN_XMLNS   = 'http://purl.org/macgirvin/dfrn/1.0'
   OS_XMLNS     = 'http://ostatus.org/schema/1.0'
-  GABSCL_XMLNS = 'http://gab.com/schema/1.0'
+  MTDN_XMLNS   = 'http://mastodon.social/schema/1.0'
 
   def unique_tag(date, id, type)
     "tag:#{Rails.configuration.x.local_domain},#{date.strftime('%Y-%m-%d')}:objectId=#{id}:objectType=#{type}"
diff --git a/app/models/remote_profile.rb b/app/models/remote_profile.rb
index 9a36d6c8..d79b8eb8 100644
--- a/app/models/remote_profile.rb
+++ b/app/models/remote_profile.rb
@@ -30,7 +30,7 @@ class RemoteProfile
   end
 
   def scope
-    @scope ||= author.at_xpath('./gabsocial:scope', gabsocial: OStatus::TagManager::GABSCL_XMLNS)&.content
+    @scope ||= author.at_xpath('./gabsocial:scope', gabsocial: OStatus::TagManager::MTDN_XMLNS)&.content
   end
 
   def avatar
diff --git a/spec/lib/ostatus/atom_serializer_spec.rb b/spec/lib/ostatus/atom_serializer_spec.rb
index 3492d119..bfb957a8 100644
--- a/spec/lib/ostatus/atom_serializer_spec.rb
+++ b/spec/lib/ostatus/atom_serializer_spec.rb
@@ -50,7 +50,7 @@ RSpec.describe OStatus::AtomSerializer do
       expect(element['xmlns:poco']).to eq OStatus::TagManager::POCO_XMLNS
       expect(element['xmlns:media']).to eq OStatus::TagManager::MEDIA_XMLNS
       expect(element['xmlns:ostatus']).to eq OStatus::TagManager::OS_XMLNS
-      expect(element['xmlns:gabsocial']).to eq OStatus::TagManager::GABSCL_XMLNS
+      expect(element['xmlns:gabsocial']).to eq OStatus::TagManager::MTDN_XMLNS
     end
   end
 
diff --git a/spec/models/remote_profile_spec.rb b/spec/models/remote_profile_spec.rb
index e334f937..cbe55105 100644
--- a/spec/models/remote_profile_spec.rb
+++ b/spec/models/remote_profile_spec.rb
@@ -92,7 +92,7 @@ RSpec.describe RemoteProfile do
     it 'calls author.at_xpath.content' do
       expect(author).to receive_message_chain(:at_xpath, :content).with(
         './gabsocial:scope',
-        gabsocial: OStatus::TagManager::GABSCL_XMLNS
+        gabsocial: OStatus::TagManager::MTDN_XMLNS
       ).with(no_args)
 
       remote_profile.scope