diff --git a/app/lib/activitypub/adapter.rb b/app/lib/activitypub/adapter.rb
index e038136c0..df132f019 100644
--- a/app/lib/activitypub/adapter.rb
+++ b/app/lib/activitypub/adapter.rb
@@ -5,6 +5,10 @@ class ActivityPub::Adapter < ActiveModelSerializers::Adapter::Base
     :camel_lower
   end
 
+  def self.transform_key_casing!(value, _options)
+    ActivityPub::CaseTransform.camel_lower(value)
+  end
+
   def serializable_hash(options = nil)
     options = serialization_options(options)
     serialized_hash = { '@context': ActivityPub::TagManager::CONTEXT }.merge(ActiveModelSerializers::Adapter::Attributes.new(serializer, instance_options).serializable_hash(options))
diff --git a/app/lib/activitypub/case_transform.rb b/app/lib/activitypub/case_transform.rb
new file mode 100644
index 000000000..7f716f862
--- /dev/null
+++ b/app/lib/activitypub/case_transform.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+module ActivityPub::CaseTransform
+  class << self
+    def camel_lower_cache
+      @camel_lower_cache ||= {}
+    end
+
+    def camel_lower(value)
+      case value
+      when Array then value.map { |item| camel_lower(item) }
+      when Hash then value.deep_transform_keys! { |key| camel_lower(key) }
+      when Symbol then camel_lower(value.to_s).to_sym
+      when String
+        camel_lower_cache[value] ||= if value.start_with?('_:')
+                                       '_:' + value.gsub(/\A_:/, '').underscore.camelize(:lower)
+                                     else
+                                       value.underscore.camelize(:lower)
+                                     end
+      else value
+      end
+    end
+  end
+end
diff --git a/app/serializers/activitypub/actor_serializer.rb b/app/serializers/activitypub/actor_serializer.rb
index 8a119603d..b15736868 100644
--- a/app/serializers/activitypub/actor_serializer.rb
+++ b/app/serializers/activitypub/actor_serializer.rb
@@ -9,6 +9,8 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
 
   has_one :public_key, serializer: ActivityPub::PublicKeySerializer
 
+  attribute :locked, key: '_:locked'
+
   class ImageSerializer < ActiveModel::Serializer
     include RoutingHelper
 
diff --git a/app/services/activitypub/process_account_service.rb b/app/services/activitypub/process_account_service.rb
index 92e2dbb30..9fb7ebf9e 100644
--- a/app/services/activitypub/process_account_service.rb
+++ b/app/services/activitypub/process_account_service.rb
@@ -46,6 +46,7 @@ class ActivityPub::ProcessAccountService < BaseService
     @account.avatar_remote_url   = image_url('icon')
     @account.header_remote_url   = image_url('image')
     @account.public_key          = public_key || ''
+    @account.locked              = @json['_:locked'] || false
     @account.save!
   end