diff --git a/app/lib/activitypub/activity/flag.rb b/app/lib/activitypub/activity/flag.rb
index b0443849a..7539bda42 100644
--- a/app/lib/activitypub/activity/flag.rb
+++ b/app/lib/activitypub/activity/flag.rb
@@ -16,7 +16,7 @@ class ActivityPub::Activity::Flag < ActivityPub::Activity
         @account,
         target_account,
         status_ids: target_statuses.nil? ? [] : target_statuses.map(&:id),
-        comment: @json['content'] || '',
+        comment: report_comment,
         uri: report_uri
       )
     end
@@ -35,4 +35,8 @@ class ActivityPub::Activity::Flag < ActivityPub::Activity
   def report_uri
     @json['id'] unless @json['id'].nil? || invalid_origin?(@json['id'])
   end
+
+  def report_comment
+    (@json['content'] || '')[0...5000]
+  end
 end
diff --git a/app/lib/activitypub/tag_manager.rb b/app/lib/activitypub/tag_manager.rb
index 3d6b28ef5..e05c06522 100644
--- a/app/lib/activitypub/tag_manager.rb
+++ b/app/lib/activitypub/tag_manager.rb
@@ -27,6 +27,8 @@ class ActivityPub::TagManager
     when :note, :comment, :activity
       return activity_account_status_url(target.account, target) if target.reblog?
       short_account_status_url(target.account, target)
+    when :flag
+      target.uri
     end
   end
 
@@ -41,6 +43,8 @@ class ActivityPub::TagManager
       account_status_url(target.account, target)
     when :emoji
       emoji_url(target)
+    when :flag
+      target.uri
     end
   end
 
diff --git a/app/models/report.rb b/app/models/report.rb
index 525d22ad5..3ae5c10dd 100644
--- a/app/models/report.rb
+++ b/app/models/report.rb
@@ -39,7 +39,10 @@ class Report < ApplicationRecord
   scope :resolved,   -> { where.not(action_taken_at: nil) }
   scope :with_accounts, -> { includes([:account, :target_account, :action_taken_by_account, :assigned_account].index_with({ user: [:invite_request, :invite] })) }
 
-  validates :comment, length: { maximum: 1_000 }
+  # A report is considered local if the reporter is local
+  delegate :local?, to: :account
+
+  validates :comment, length: { maximum: 1_000 }, if: :local?
   validates :rule_ids, absence: true, unless: :violation?
 
   validate :validate_rule_ids
@@ -50,10 +53,6 @@ class Report < ApplicationRecord
     violation: 2_000,
   }
 
-  def local?
-    false # Force uri_for to use uri attribute
-  end
-
   before_validation :set_uri, only: :create
 
   after_create_commit :trigger_webhooks
diff --git a/spec/lib/activitypub/activity/flag_spec.rb b/spec/lib/activitypub/activity/flag_spec.rb
index 2f2d13876..6d7a8a7ec 100644
--- a/spec/lib/activitypub/activity/flag_spec.rb
+++ b/spec/lib/activitypub/activity/flag_spec.rb
@@ -37,6 +37,37 @@ RSpec.describe ActivityPub::Activity::Flag do
       end
     end
 
+    context 'when the report comment is excessively long' do
+      subject do
+        described_class.new({
+          '@context': 'https://www.w3.org/ns/activitystreams',
+          id: flag_id,
+          type: 'Flag',
+          content: long_comment,
+          actor: ActivityPub::TagManager.instance.uri_for(sender),
+          object: [
+            ActivityPub::TagManager.instance.uri_for(flagged),
+            ActivityPub::TagManager.instance.uri_for(status),
+          ],
+        }.with_indifferent_access, sender)
+      end
+
+      let(:long_comment) { Faker::Lorem.characters(number: 6000) }
+
+      before do
+        subject.perform
+      end
+
+      it 'creates a report but with a truncated comment' do
+        report = Report.find_by(account: sender, target_account: flagged)
+
+        expect(report).to_not be_nil
+        expect(report.comment.length).to eq 5000
+        expect(report.comment).to eq long_comment[0...5000]
+        expect(report.status_ids).to eq [status.id]
+      end
+    end
+
     context 'when the reported status is private and should not be visible to the remote server' do
       let(:status) { Fabricate(:status, account: flagged, uri: 'foobar', visibility: :private) }
 
diff --git a/spec/models/report_spec.rb b/spec/models/report_spec.rb
index 874be4132..c485a4a3c 100644
--- a/spec/models/report_spec.rb
+++ b/spec/models/report_spec.rb
@@ -125,10 +125,17 @@ describe Report do
       expect(report).to be_valid
     end
 
-    it 'is invalid if comment is longer than 1000 characters' do
+    let(:remote_account) { Fabricate(:account, domain: 'example.com', protocol: :activitypub, inbox_url: 'http://example.com/inbox') }
+
+    it 'is invalid if comment is longer than 1000 characters only if reporter is local' do
       report = Fabricate.build(:report, comment: Faker::Lorem.characters(number: 1001))
-      report.valid?
+      expect(report.valid?).to be false
       expect(report).to model_have_error_on_field(:comment)
     end
+
+    it 'is valid if comment is longer than 1000 characters and reporter is not local' do
+      report = Fabricate.build(:report, account: remote_account, comment: Faker::Lorem.characters(number: 1001))
+      expect(report.valid?).to be true
+    end
   end
 end
diff --git a/spec/services/report_service_spec.rb b/spec/services/report_service_spec.rb
index 02bc42ac1..1737a05ae 100644
--- a/spec/services/report_service_spec.rb
+++ b/spec/services/report_service_spec.rb
@@ -4,6 +4,14 @@ RSpec.describe ReportService, type: :service do
   subject { described_class.new }
 
   let(:source_account) { Fabricate(:account) }
+  let(:target_account) { Fabricate(:account) }
+
+  context 'with a local account' do
+    it 'has a uri' do
+      report = subject.call(source_account, target_account)
+      expect(report.uri).to_not be_nil
+    end
+  end
 
   context 'for a remote account' do
     let(:remote_account) { Fabricate(:account, domain: 'example.com', protocol: :activitypub, inbox_url: 'http://example.com/inbox') }