diff --git a/spec/lib/activitypub/activity/announce_spec.rb b/spec/lib/activitypub/activity/announce_spec.rb
index b556bfd6c2..582dd4d63f 100644
--- a/spec/lib/activitypub/activity/announce_spec.rb
+++ b/spec/lib/activitypub/activity/announce_spec.rb
@@ -35,7 +35,7 @@ RSpec.describe ActivityPub::Activity::Announce do
     context 'when sender is followed by a local account' do
       before do
         Fabricate(:account).follow!(sender)
-        stub_request(:get, 'https://example.com/actor/hello-world').to_return(body: Oj.dump(unknown_object_json), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/actor/hello-world').to_return(body: JSON.dump(unknown_object_json), headers: { 'Content-Type': 'application/activity+json' })
         subject.perform
       end
 
@@ -120,7 +120,7 @@ RSpec.describe ActivityPub::Activity::Announce do
       let(:object_json) { 'https://example.com/actor/hello-world' }
 
       before do
-        stub_request(:get, 'https://example.com/actor/hello-world').to_return(body: Oj.dump(unknown_object_json), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/actor/hello-world').to_return(body: JSON.dump(unknown_object_json), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       context 'when the relay is enabled' do
diff --git a/spec/lib/activitypub/activity/create_spec.rb b/spec/lib/activitypub/activity/create_spec.rb
index 8be6766dad..721b30e0fa 100644
--- a/spec/lib/activitypub/activity/create_spec.rb
+++ b/spec/lib/activitypub/activity/create_spec.rb
@@ -1071,7 +1071,7 @@ RSpec.describe ActivityPub::Activity::Create do
       before do
         stub_request(:get, object_json[:id])
           .with(headers: { Authorization: "Bearer #{token}" })
-          .to_return(body: Oj.dump(object_json), headers: { 'Content-Type': 'application/activity+json' })
+          .to_return(body: JSON.dump(object_json), headers: { 'Content-Type': 'application/activity+json' })
 
         subject.perform
       end
diff --git a/spec/lib/activitypub/dereferencer_spec.rb b/spec/lib/activitypub/dereferencer_spec.rb
index 11078de866..de9195612c 100644
--- a/spec/lib/activitypub/dereferencer_spec.rb
+++ b/spec/lib/activitypub/dereferencer_spec.rb
@@ -12,7 +12,7 @@ RSpec.describe ActivityPub::Dereferencer do
     let(:uri) { nil }
 
     before do
-      stub_request(:get, 'https://example.com/foo').to_return(body: Oj.dump(object), headers: { 'Content-Type' => 'application/activity+json' })
+      stub_request(:get, 'https://example.com/foo').to_return(body: JSON.dump(object), headers: { 'Content-Type' => 'application/activity+json' })
     end
 
     context 'with a URI' do
diff --git a/spec/lib/feed_manager_spec.rb b/spec/lib/feed_manager_spec.rb
index 1d3123d343..7a7fd371b1 100644
--- a/spec/lib/feed_manager_spec.rb
+++ b/spec/lib/feed_manager_spec.rb
@@ -524,7 +524,7 @@ RSpec.describe FeedManager do
       allow(redis).to receive_messages(publish: nil)
       subject.unpush_from_home(receiver, status)
 
-      deletion = Oj.dump(event: :delete, payload: status.id.to_s)
+      deletion = JSON.dump(event: :delete, payload: status.id.to_s)
       expect(redis).to have_received(:publish).with("timeline:#{receiver.id}", deletion)
     end
   end
diff --git a/spec/lib/mastodon/cli/domains_spec.rb b/spec/lib/mastodon/cli/domains_spec.rb
index d1c26546f0..6034921ef8 100644
--- a/spec/lib/mastodon/cli/domains_spec.rb
+++ b/spec/lib/mastodon/cli/domains_spec.rb
@@ -87,7 +87,7 @@ RSpec.describe Mastodon::CLI::Domains do
         end
 
         def json_summary
-          Oj.dump('host.example': { activity: {} })
+          JSON.dump('host.example': { activity: {} })
         end
       end
     end
diff --git a/spec/lib/webfinger_spec.rb b/spec/lib/webfinger_spec.rb
index 5015deac7f..9b4e9b5d67 100644
--- a/spec/lib/webfinger_spec.rb
+++ b/spec/lib/webfinger_spec.rb
@@ -8,7 +8,7 @@ RSpec.describe Webfinger do
       let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/activity+json' }] } }
 
       it 'correctly parses the response' do
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
 
         response = described_class.new('acct:alice@example.com').perform
 
@@ -20,7 +20,7 @@ RSpec.describe Webfinger do
       let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"' }] } }
 
       it 'correctly parses the response' do
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
 
         response = described_class.new('acct:alice@example.com').perform
 
@@ -32,7 +32,7 @@ RSpec.describe Webfinger do
       let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/json"' }] } }
 
       it 'raises an error' do
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
 
         expect { described_class.new('acct:alice@example.com').perform }.to raise_error(Webfinger::Error)
       end
diff --git a/spec/lib/webhooks/payload_renderer_spec.rb b/spec/lib/webhooks/payload_renderer_spec.rb
index 0623edd254..71171dfd74 100644
--- a/spec/lib/webhooks/payload_renderer_spec.rb
+++ b/spec/lib/webhooks/payload_renderer_spec.rb
@@ -7,7 +7,7 @@ RSpec.describe Webhooks::PayloadRenderer do
 
   let(:event)   { Webhooks::EventPresenter.new(type, object) }
   let(:payload) { ActiveModelSerializers::SerializableResource.new(event, serializer: REST::Admin::WebhookEventSerializer, scope: nil, scope_name: :current_user).as_json }
-  let(:json)    { Oj.dump(payload) }
+  let(:json)    { JSON.dump(payload) }
 
   describe '#render' do
     context 'when event is account.approved' do
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index 08d410bb16..ebb8194bbe 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -506,7 +506,7 @@ RSpec.describe User do
       expect { web_push_subscription.reload }
         .to raise_error(ActiveRecord::RecordNotFound)
       expect(redis_pipeline_stub)
-        .to have_received(:publish).with("timeline:access_token:#{access_token.id}", Oj.dump(event: :kill)).once
+        .to have_received(:publish).with("timeline:access_token:#{access_token.id}", JSON.dump(event: :kill)).once
     end
 
     def remove_activated_sessions
diff --git a/spec/requests/api/v2/filters_spec.rb b/spec/requests/api/v2/filters_spec.rb
index 3b5c44cefa..9657ca5997 100644
--- a/spec/requests/api/v2/filters_spec.rb
+++ b/spec/requests/api/v2/filters_spec.rb
@@ -210,7 +210,7 @@ RSpec.describe 'Filters' do
 
         expect(keyword.reload.keyword).to eq 'updated'
 
-        expect(redis).to have_received(:publish).with("timeline:#{user.account.id}", Oj.dump(event: :filters_changed)).once
+        expect(redis).to have_received(:publish).with("timeline:#{user.account.id}", JSON.dump(event: :filters_changed)).once
       end
     end
 
diff --git a/spec/services/activitypub/fetch_featured_collection_service_spec.rb b/spec/services/activitypub/fetch_featured_collection_service_spec.rb
index 7ea87922ac..3472b67f5d 100644
--- a/spec/services/activitypub/fetch_featured_collection_service_spec.rb
+++ b/spec/services/activitypub/fetch_featured_collection_service_spec.rb
@@ -72,11 +72,11 @@ RSpec.describe ActivityPub::FetchFeaturedCollectionService do
 
   shared_examples 'sets pinned posts' do
     before do
-      stub_request(:get, 'https://example.com/account/pinned/known').to_return(status: 200, body: Oj.dump(status_json_pinned_known), headers: { 'Content-Type': 'application/activity+json' })
-      stub_request(:get, 'https://example.com/account/pinned/unknown-inlined').to_return(status: 200, body: Oj.dump(status_json_pinned_unknown_inlined), headers: { 'Content-Type': 'application/activity+json' })
+      stub_request(:get, 'https://example.com/account/pinned/known').to_return(status: 200, body: JSON.dump(status_json_pinned_known), headers: { 'Content-Type': 'application/activity+json' })
+      stub_request(:get, 'https://example.com/account/pinned/unknown-inlined').to_return(status: 200, body: JSON.dump(status_json_pinned_unknown_inlined), headers: { 'Content-Type': 'application/activity+json' })
       stub_request(:get, 'https://example.com/account/pinned/unknown-unreachable').to_return(status: 404)
-      stub_request(:get, 'https://example.com/account/pinned/unknown-reachable').to_return(status: 200, body: Oj.dump(status_json_pinned_unknown_reachable), headers: { 'Content-Type': 'application/activity+json' })
-      stub_request(:get, 'https://example.com/account/collections/featured').to_return(status: 200, body: Oj.dump(featured_with_null), headers: { 'Content-Type': 'application/activity+json' })
+      stub_request(:get, 'https://example.com/account/pinned/unknown-reachable').to_return(status: 200, body: JSON.dump(status_json_pinned_unknown_reachable), headers: { 'Content-Type': 'application/activity+json' })
+      stub_request(:get, 'https://example.com/account/collections/featured').to_return(status: 200, body: JSON.dump(featured_with_null), headers: { 'Content-Type': 'application/activity+json' })
 
       subject.call(actor, note: true, hashtag: false)
     end
@@ -94,7 +94,7 @@ RSpec.describe ActivityPub::FetchFeaturedCollectionService do
   describe '#call' do
     context 'when the endpoint is a Collection' do
       before do
-        stub_request(:get, actor.featured_collection_url).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, actor.featured_collection_url).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it_behaves_like 'sets pinned posts'
@@ -111,7 +111,7 @@ RSpec.describe ActivityPub::FetchFeaturedCollectionService do
       end
 
       before do
-        stub_request(:get, actor.featured_collection_url).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, actor.featured_collection_url).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it_behaves_like 'sets pinned posts'
@@ -120,7 +120,7 @@ RSpec.describe ActivityPub::FetchFeaturedCollectionService do
         let(:items) { 'https://example.com/account/pinned/unknown-reachable' }
 
         before do
-          stub_request(:get, 'https://example.com/account/pinned/unknown-reachable').to_return(status: 200, body: Oj.dump(status_json_pinned_unknown_reachable), headers: { 'Content-Type': 'application/activity+json' })
+          stub_request(:get, 'https://example.com/account/pinned/unknown-reachable').to_return(status: 200, body: JSON.dump(status_json_pinned_unknown_reachable), headers: { 'Content-Type': 'application/activity+json' })
           subject.call(actor, note: true, hashtag: false)
         end
 
@@ -147,7 +147,7 @@ RSpec.describe ActivityPub::FetchFeaturedCollectionService do
       end
 
       before do
-        stub_request(:get, actor.featured_collection_url).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, actor.featured_collection_url).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it_behaves_like 'sets pinned posts'
@@ -156,7 +156,7 @@ RSpec.describe ActivityPub::FetchFeaturedCollectionService do
         let(:items) { 'https://example.com/account/pinned/unknown-reachable' }
 
         before do
-          stub_request(:get, 'https://example.com/account/pinned/unknown-reachable').to_return(status: 200, body: Oj.dump(status_json_pinned_unknown_reachable), headers: { 'Content-Type': 'application/activity+json' })
+          stub_request(:get, 'https://example.com/account/pinned/unknown-reachable').to_return(status: 200, body: JSON.dump(status_json_pinned_unknown_reachable), headers: { 'Content-Type': 'application/activity+json' })
           subject.call(actor, note: true, hashtag: false)
         end
 
diff --git a/spec/services/activitypub/fetch_featured_tags_collection_service_spec.rb b/spec/services/activitypub/fetch_featured_tags_collection_service_spec.rb
index 59367b1e32..0bd70953ac 100644
--- a/spec/services/activitypub/fetch_featured_tags_collection_service_spec.rb
+++ b/spec/services/activitypub/fetch_featured_tags_collection_service_spec.rb
@@ -38,7 +38,7 @@ RSpec.describe ActivityPub::FetchFeaturedTagsCollectionService do
   describe '#call' do
     context 'when the endpoint is a Collection' do
       before do
-        stub_request(:get, collection_url).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, collection_url).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it_behaves_like 'sets featured tags'
@@ -46,7 +46,7 @@ RSpec.describe ActivityPub::FetchFeaturedTagsCollectionService do
 
     context 'when the account already has featured tags' do
       before do
-        stub_request(:get, collection_url).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, collection_url).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
 
         actor.featured_tags.create!(name: 'FoO')
         actor.featured_tags.create!(name: 'baz')
@@ -67,7 +67,7 @@ RSpec.describe ActivityPub::FetchFeaturedTagsCollectionService do
       end
 
       before do
-        stub_request(:get, collection_url).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, collection_url).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it_behaves_like 'sets featured tags'
@@ -88,7 +88,7 @@ RSpec.describe ActivityPub::FetchFeaturedTagsCollectionService do
       end
 
       before do
-        stub_request(:get, collection_url).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, collection_url).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it_behaves_like 'sets featured tags'
diff --git a/spec/services/activitypub/fetch_remote_account_service_spec.rb b/spec/services/activitypub/fetch_remote_account_service_spec.rb
index 175ac9cb61..d19181448f 100644
--- a/spec/services/activitypub/fetch_remote_account_service_spec.rb
+++ b/spec/services/activitypub/fetch_remote_account_service_spec.rb
@@ -38,8 +38,8 @@ RSpec.describe ActivityPub::FetchRemoteAccountService do
       before do
         actor[:inbox] = nil
 
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and returns nil' do
@@ -54,8 +54,8 @@ RSpec.describe ActivityPub::FetchRemoteAccountService do
       let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/activity+json' }] } }
 
       before do
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and sets attributes' do
@@ -75,9 +75,9 @@ RSpec.describe ActivityPub::FetchRemoteAccountService do
       let!(:webfinger) { { subject: 'acct:alice@iscool.af', links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/activity+json' }] } }
 
       before do
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
-        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and follows redirection and sets attributes' do
@@ -98,8 +98,8 @@ RSpec.describe ActivityPub::FetchRemoteAccountService do
       let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/bob', type: 'application/activity+json' }] } }
 
       before do
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and does not create account' do
@@ -114,9 +114,9 @@ RSpec.describe ActivityPub::FetchRemoteAccountService do
       let!(:webfinger) { { subject: 'acct:alice@iscool.af', links: [{ rel: 'self', href: 'https://example.com/bob', type: 'application/activity+json' }] } }
 
       before do
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
-        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and follows redirect and does not create account' do
@@ -130,7 +130,7 @@ RSpec.describe ActivityPub::FetchRemoteAccountService do
 
     context 'with wrong id' do
       it 'does not create account' do
-        expect(subject.call('https://fake.address/@foo', prefetched_body: Oj.dump(actor))).to be_nil
+        expect(subject.call('https://fake.address/@foo', prefetched_body: JSON.dump(actor))).to be_nil
       end
     end
   end
diff --git a/spec/services/activitypub/fetch_remote_actor_service_spec.rb b/spec/services/activitypub/fetch_remote_actor_service_spec.rb
index 9d031cb89b..09a1383b07 100644
--- a/spec/services/activitypub/fetch_remote_actor_service_spec.rb
+++ b/spec/services/activitypub/fetch_remote_actor_service_spec.rb
@@ -38,8 +38,8 @@ RSpec.describe ActivityPub::FetchRemoteActorService do
       before do
         actor[:inbox] = nil
 
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and returns nil' do
@@ -54,8 +54,8 @@ RSpec.describe ActivityPub::FetchRemoteActorService do
       let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/activity+json' }] } }
 
       before do
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and sets values' do
@@ -75,9 +75,9 @@ RSpec.describe ActivityPub::FetchRemoteActorService do
       let!(:webfinger) { { subject: 'acct:alice@iscool.af', links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/activity+json' }] } }
 
       before do
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
-        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and follows redirect and sets values' do
@@ -98,8 +98,8 @@ RSpec.describe ActivityPub::FetchRemoteActorService do
       let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/bob', type: 'application/activity+json' }] } }
 
       before do
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and does not create account' do
@@ -114,9 +114,9 @@ RSpec.describe ActivityPub::FetchRemoteActorService do
       let!(:webfinger) { { subject: 'acct:alice@iscool.af', links: [{ rel: 'self', href: 'https://example.com/bob', type: 'application/activity+json' }] } }
 
       before do
-        stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
-        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+        stub_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       end
 
       it 'fetches resource and looks up webfinger and follows redirect and does not create account' do
@@ -130,7 +130,7 @@ RSpec.describe ActivityPub::FetchRemoteActorService do
 
     context 'with wrong id' do
       it 'does not create account' do
-        expect(subject.call('https://fake.address/@foo', prefetched_body: Oj.dump(actor))).to be_nil
+        expect(subject.call('https://fake.address/@foo', prefetched_body: JSON.dump(actor))).to be_nil
       end
     end
   end
diff --git a/spec/services/activitypub/fetch_remote_key_service_spec.rb b/spec/services/activitypub/fetch_remote_key_service_spec.rb
index 847a154108..98d01c5a00 100644
--- a/spec/services/activitypub/fetch_remote_key_service_spec.rb
+++ b/spec/services/activitypub/fetch_remote_key_service_spec.rb
@@ -50,8 +50,8 @@ RSpec.describe ActivityPub::FetchRemoteKeyService do
   end
 
   before do
-    stub_request(:get, 'https://example.com/alice').to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
-    stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+    stub_request(:get, 'https://example.com/alice').to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+    stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
   end
 
   describe '#call' do
@@ -59,7 +59,7 @@ RSpec.describe ActivityPub::FetchRemoteKeyService do
 
     context 'when the key is a sub-object from the actor' do
       before do
-        stub_request(:get, public_key_id).to_return(body: Oj.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, public_key_id).to_return(body: JSON.dump(actor), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it 'returns the expected account' do
@@ -71,7 +71,7 @@ RSpec.describe ActivityPub::FetchRemoteKeyService do
       let(:public_key_id) { 'https://example.com/alice-public-key.json' }
 
       before do
-        stub_request(:get, public_key_id).to_return(body: Oj.dump(key_json.merge({ '@context': ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1'] })), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, public_key_id).to_return(body: JSON.dump(key_json.merge({ '@context': ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1'] })), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it 'returns the expected account' do
@@ -84,7 +84,7 @@ RSpec.describe ActivityPub::FetchRemoteKeyService do
       let(:actor_public_key) { 'https://example.com/alice-public-key.json' }
 
       before do
-        stub_request(:get, public_key_id).to_return(body: Oj.dump(key_json.merge({ '@context': ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1'] })), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, public_key_id).to_return(body: JSON.dump(key_json.merge({ '@context': ['https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1'] })), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it 'returns the nil' do
diff --git a/spec/services/activitypub/fetch_remote_status_service_spec.rb b/spec/services/activitypub/fetch_remote_status_service_spec.rb
index 9d8c6e0e0a..bed618935f 100644
--- a/spec/services/activitypub/fetch_remote_status_service_spec.rb
+++ b/spec/services/activitypub/fetch_remote_status_service_spec.rb
@@ -23,13 +23,13 @@ RSpec.describe ActivityPub::FetchRemoteStatusService do
 
   before do
     stub_request(:get, 'https://foo.bar/watch?v=12345').to_return(status: 404, body: '')
-    stub_request(:get, object[:id]).to_return(body: Oj.dump(object))
+    stub_request(:get, object[:id]).to_return(body: JSON.dump(object))
   end
 
   describe '#call' do
     before do
       existing_status
-      subject.call(object[:id], prefetched_body: Oj.dump(object))
+      subject.call(object[:id], prefetched_body: JSON.dump(object))
     end
 
     context 'with Note object' do
@@ -309,7 +309,7 @@ RSpec.describe ActivityPub::FetchRemoteStatusService do
       end
 
       it 'creates statuses but not more than limit allows' do
-        expect { subject.call(object[:id], prefetched_body: Oj.dump(object)) }
+        expect { subject.call(object[:id], prefetched_body: JSON.dump(object)) }
           .to change { sender.statuses.count }.by_at_least(2)
           .and change { sender.statuses.count }.by_at_most(3)
       end
@@ -359,7 +359,7 @@ RSpec.describe ActivityPub::FetchRemoteStatusService do
       end
 
       it 'creates statuses but not more than limit allows' do
-        expect { subject.call(object[:id], prefetched_body: Oj.dump(object)) }
+        expect { subject.call(object[:id], prefetched_body: JSON.dump(object)) }
           .to change { sender.statuses.count }.by_at_least(2)
           .and change { sender.statuses.count }.by_at_most(3)
       end
diff --git a/spec/services/activitypub/fetch_replies_service_spec.rb b/spec/services/activitypub/fetch_replies_service_spec.rb
index e7d8d3528a..5b919d9355 100644
--- a/spec/services/activitypub/fetch_replies_service_spec.rb
+++ b/spec/services/activitypub/fetch_replies_service_spec.rb
@@ -58,7 +58,7 @@ RSpec.describe ActivityPub::FetchRepliesService do
 
       context 'when passing the URL to the collection' do
         before do
-          stub_request(:get, collection_uri).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+          stub_request(:get, collection_uri).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
         end
 
         it 'spawns workers for up to 5 replies on the same server' do
@@ -93,7 +93,7 @@ RSpec.describe ActivityPub::FetchRepliesService do
 
       context 'when passing the URL to the collection' do
         before do
-          stub_request(:get, collection_uri).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+          stub_request(:get, collection_uri).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
         end
 
         it 'spawns workers for up to 5 replies on the same server' do
@@ -132,7 +132,7 @@ RSpec.describe ActivityPub::FetchRepliesService do
 
       context 'when passing the URL to the collection' do
         before do
-          stub_request(:get, collection_uri).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+          stub_request(:get, collection_uri).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
         end
 
         it 'spawns workers for up to 5 replies on the same server' do
diff --git a/spec/services/activitypub/process_collection_service_spec.rb b/spec/services/activitypub/process_collection_service_spec.rb
index 74df0f9106..c7f090be08 100644
--- a/spec/services/activitypub/process_collection_service_spec.rb
+++ b/spec/services/activitypub/process_collection_service_spec.rb
@@ -21,7 +21,7 @@ RSpec.describe ActivityPub::ProcessCollectionService do
     }
   end
 
-  let(:json) { Oj.dump(payload) }
+  let(:json) { JSON.dump(payload) }
 
   describe '#call' do
     context 'when actor is suspended' do
diff --git a/spec/services/activitypub/process_status_update_service_spec.rb b/spec/services/activitypub/process_status_update_service_spec.rb
index 1a8ea2d170..b9011d28f0 100644
--- a/spec/services/activitypub/process_status_update_service_spec.rb
+++ b/spec/services/activitypub/process_status_update_service_spec.rb
@@ -22,7 +22,7 @@ RSpec.describe ActivityPub::ProcessStatusUpdateService do
       ],
     }
   end
-  let(:json) { Oj.load(Oj.dump(payload)) }
+  let(:json) { JSON.parse(JSON.dump(payload)) }
 
   let(:alice) { Fabricate(:account) }
   let(:bob) { Fabricate(:account) }
diff --git a/spec/services/activitypub/synchronize_followers_service_spec.rb b/spec/services/activitypub/synchronize_followers_service_spec.rb
index 974368b7d7..ee653b841b 100644
--- a/spec/services/activitypub/synchronize_followers_service_spec.rb
+++ b/spec/services/activitypub/synchronize_followers_service_spec.rb
@@ -53,7 +53,7 @@ RSpec.describe ActivityPub::SynchronizeFollowersService do
   describe '#call' do
     context 'when the endpoint is a Collection of actor URIs' do
       before do
-        stub_request(:get, collection_uri).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, collection_uri).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it_behaves_like 'synchronizes followers'
@@ -70,7 +70,7 @@ RSpec.describe ActivityPub::SynchronizeFollowersService do
       end
 
       before do
-        stub_request(:get, collection_uri).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, collection_uri).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it_behaves_like 'synchronizes followers'
@@ -91,7 +91,7 @@ RSpec.describe ActivityPub::SynchronizeFollowersService do
       end
 
       before do
-        stub_request(:get, collection_uri).to_return(status: 200, body: Oj.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
+        stub_request(:get, collection_uri).to_return(status: 200, body: JSON.dump(payload), headers: { 'Content-Type': 'application/activity+json' })
       end
 
       it_behaves_like 'synchronizes followers'
diff --git a/spec/services/backup_service_spec.rb b/spec/services/backup_service_spec.rb
index 878405a0fe..1dcebc24d2 100644
--- a/spec/services/backup_service_spec.rb
+++ b/spec/services/backup_service_spec.rb
@@ -56,7 +56,7 @@ RSpec.describe BackupService do
 
   def expect_outbox_export
     body = export_json_raw(:outbox)
-    json = Oj.load(body)
+    json = JSON.parse(body)
 
     aggregate_failures do
       expect(body.scan('@context').count).to eq 1
@@ -93,7 +93,7 @@ RSpec.describe BackupService do
   end
 
   def export_json(type)
-    Oj.load(export_json_raw(type))
+    JSON.parse(export_json_raw(type))
   end
 
   def include_create_item(status)
diff --git a/spec/services/fetch_remote_status_service_spec.rb b/spec/services/fetch_remote_status_service_spec.rb
index a9c61e7b4e..7c10cd96da 100644
--- a/spec/services/fetch_remote_status_service_spec.rb
+++ b/spec/services/fetch_remote_status_service_spec.rb
@@ -19,7 +19,7 @@ RSpec.describe FetchRemoteStatusService do
   context 'when protocol is :activitypub' do
     subject { described_class.new.call(note[:id], prefetched_body: prefetched_body) }
 
-    let(:prefetched_body) { Oj.dump(note) }
+    let(:prefetched_body) { JSON.dump(note) }
 
     before do
       subject
diff --git a/spec/services/remove_status_service_spec.rb b/spec/services/remove_status_service_spec.rb
index f2b46f05b0..3b54c25d1d 100644
--- a/spec/services/remove_status_service_spec.rb
+++ b/spec/services/remove_status_service_spec.rb
@@ -40,7 +40,7 @@ RSpec.describe RemoveStatusService, :inline_jobs do
         .to_not include(status.id)
 
       expect(redis)
-        .to have_received(:publish).with('timeline:public:media', Oj.dump(event: :delete, payload: status.id.to_s))
+        .to have_received(:publish).with('timeline:public:media', JSON.dump(event: :delete, payload: status.id.to_s))
 
       expect(delete_delivery(hank, status))
         .to have_been_made.once
diff --git a/spec/services/resolve_account_service_spec.rb b/spec/services/resolve_account_service_spec.rb
index 1bd4e9a8e3..211f35ad0d 100644
--- a/spec/services/resolve_account_service_spec.rb
+++ b/spec/services/resolve_account_service_spec.rb
@@ -103,7 +103,7 @@ RSpec.describe ResolveAccountService do
   context 'with a legitimate webfinger redirection' do
     before do
       webfinger = { subject: 'acct:foo@ap.example.com', links: [{ rel: 'self', href: 'https://ap.example.com/users/foo', type: 'application/activity+json' }] }
-      stub_request(:get, 'https://redirected.example.com/.well-known/webfinger?resource=acct:Foo@redirected.example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+      stub_request(:get, 'https://redirected.example.com/.well-known/webfinger?resource=acct:Foo@redirected.example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
     end
 
     it 'returns new remote account' do
@@ -121,7 +121,7 @@ RSpec.describe ResolveAccountService do
   context 'with a misconfigured redirection' do
     before do
       webfinger = { subject: 'acct:Foo@redirected.example.com', links: [{ rel: 'self', href: 'https://ap.example.com/users/foo', type: 'application/activity+json' }] }
-      stub_request(:get, 'https://redirected.example.com/.well-known/webfinger?resource=acct:Foo@redirected.example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+      stub_request(:get, 'https://redirected.example.com/.well-known/webfinger?resource=acct:Foo@redirected.example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
     end
 
     it 'returns new remote account' do
@@ -139,9 +139,9 @@ RSpec.describe ResolveAccountService do
   context 'with too many webfinger redirections' do
     before do
       webfinger = { subject: 'acct:foo@evil.example.com', links: [{ rel: 'self', href: 'https://ap.example.com/users/foo', type: 'application/activity+json' }] }
-      stub_request(:get, 'https://redirected.example.com/.well-known/webfinger?resource=acct:Foo@redirected.example.com').to_return(body: Oj.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
+      stub_request(:get, 'https://redirected.example.com/.well-known/webfinger?resource=acct:Foo@redirected.example.com').to_return(body: JSON.dump(webfinger), headers: { 'Content-Type': 'application/jrd+json' })
       webfinger2 = { subject: 'acct:foo@ap.example.com', links: [{ rel: 'self', href: 'https://ap.example.com/users/foo', type: 'application/activity+json' }] }
-      stub_request(:get, 'https://evil.example.com/.well-known/webfinger?resource=acct:foo@evil.example.com').to_return(body: Oj.dump(webfinger2), headers: { 'Content-Type': 'application/jrd+json' })
+      stub_request(:get, 'https://evil.example.com/.well-known/webfinger?resource=acct:foo@evil.example.com').to_return(body: JSON.dump(webfinger2), headers: { 'Content-Type': 'application/jrd+json' })
     end
 
     it 'does not return a new remote account' do
@@ -150,7 +150,7 @@ RSpec.describe ResolveAccountService do
   end
 
   context 'with webfinger response subject missing a host value' do
-    let(:body) { Oj.dump({ subject: 'user@' }) }
+    let(:body) { JSON.dump({ subject: 'user@' }) }
     let(:url) { 'https://host.example/.well-known/webfinger?resource=acct:user@host.example' }
 
     before do
diff --git a/spec/services/software_update_check_service_spec.rb b/spec/services/software_update_check_service_spec.rb
index 73ffe6b899..30d841b4a0 100644
--- a/spec/services/software_update_check_service_spec.rb
+++ b/spec/services/software_update_check_service_spec.rb
@@ -82,7 +82,7 @@ RSpec.describe SoftwareUpdateCheckService do
       end
 
       before do
-        stub_request(:get, full_update_check_url).to_return(body: Oj.dump(server_json))
+        stub_request(:get, full_update_check_url).to_return(body: JSON.dump(server_json))
       end
 
       it 'updates the list of known updates' do
diff --git a/spec/workers/activitypub/fetch_replies_worker_spec.rb b/spec/workers/activitypub/fetch_replies_worker_spec.rb
index 56d19705a4..10980040c8 100644
--- a/spec/workers/activitypub/fetch_replies_worker_spec.rb
+++ b/spec/workers/activitypub/fetch_replies_worker_spec.rb
@@ -17,7 +17,7 @@ RSpec.describe ActivityPub::FetchRepliesWorker do
     }
   end
 
-  let(:json) { Oj.dump(payload) }
+  let(:json) { JSON.dump(payload) }
 
   describe 'perform' do
     it 'performs a request if the collection URI is from the same host' do