diff --git a/WcaOnRails/Gemfile b/WcaOnRails/Gemfile
index 06d9ceabfe..8a67aac42b 100644
--- a/WcaOnRails/Gemfile
+++ b/WcaOnRails/Gemfile
@@ -102,7 +102,6 @@ gem 'sprockets-rails'
 gem 'fuzzy-string-match'
 gem 'sidekiq'
 gem 'sidekiq-cron'
-gem 'deep_merge', require: 'deep_merge/rails_compat'
 
 group :development, :test do
   gem 'spring'
diff --git a/WcaOnRails/Gemfile.lock b/WcaOnRails/Gemfile.lock
index b2eb761b5c..1a9fdcf75a 100644
--- a/WcaOnRails/Gemfile.lock
+++ b/WcaOnRails/Gemfile.lock
@@ -238,7 +238,6 @@ GEM
     date (3.3.3)
     debug_inspector (1.0.0)
     declarative (0.0.20)
-    deep_merge (1.2.2)
     devise (4.9.2)
       bcrypt (~> 3.0)
       orm_adapter (~> 0.1)
@@ -776,7 +775,6 @@ DEPENDENCIES
   daemons
   database_cleaner
   datetimepicker-rails!
-  deep_merge
   devise
   devise-bootstrap-views
   devise-i18n
diff --git a/WcaOnRails/app/controllers/api/v0/competitions_controller.rb b/WcaOnRails/app/controllers/api/v0/competitions_controller.rb
index 87466e9e74..91992b85d8 100644
--- a/WcaOnRails/app/controllers/api/v0/competitions_controller.rb
+++ b/WcaOnRails/app/controllers/api/v0/competitions_controller.rb
@@ -17,19 +17,22 @@ def index
     paginate json: competitions
   end
 
-  COMPETITION_INFO_SERIALIZE_OPTIONS = {
-    only: %w[extra_registration_requirements enable_donations refund_policy_limit_date event_change_deadline_date waiting_list_deadline_date on_the_spot_registration on_the_spot_entry_fee_lowest_denomination qualification_results
-             event_restrictions base_entry_fee_lowest_denomination currency_code allow_registration_edits allow_registration_self_delete_after_acceptance allow_registration_without_qualification refund_policy_percent
-             use_wca_registration guests_per_registration_limit venue contact force_comment_in_registration use_wca_registration external_registration_page guests_entry_fee_lowest_denomination guest_entry_status information],
-    methods: %w[registration_opened? main_event_id number_of_bookmarks using_stripe_payments? uses_qualification? uses_cutoff?],
-    include: %w[tabs],
-  }.freeze
-
   def show
     competition = competition_from_params
 
     if stale?(competition)
-      render json: competition.as_json(COMPETITION_INFO_SERIALIZE_OPTIONS)
+      options = {
+        only: %w[id name website start_date registration_open registration_close
+                 announced_at cancelled_at end_date competitor_limit
+                 extra_registration_requirements enable_donations refund_policy_limit_date event_change_deadline_date waiting_list_deadline_date on_the_spot_registration on_the_spot_entry_fee_lowest_denomination qualification_results
+                 event_restrictions base_entry_fee_lowest_denomination currency_code allow_registration_edits allow_registration_self_delete_after_acceptance allow_registration_without_qualification refund_policy_percent
+                 use_wca_registration guests_per_registration_limit venue contact force_comment_in_registration use_wca_registration external_registration_page guests_entry_fee_lowest_denomination guest_entry_status information],
+        methods: %w[url website short_name city venue_address venue_details latitude_degrees
+                    longitude_degrees country_iso2 event_ids
+                    registration_opened? main_event_id number_of_bookmarks using_stripe_payments? uses_qualification? uses_cutoff?],
+        include: %w[delegates organizers tabs],
+      }
+      render json: competition.as_json(options)
     end
   end
 
diff --git a/WcaOnRails/app/models/competition.rb b/WcaOnRails/app/models/competition.rb
index dac3f01b5b..615a6fbcda 100644
--- a/WcaOnRails/app/models/competition.rb
+++ b/WcaOnRails/app/models/competition.rb
@@ -1915,10 +1915,12 @@ def url
   }.freeze
 
   def serializable_hash(options = nil)
-    # This looks weird, but we need the 'deeper_merge' method to handle arrays inside hashes.
-    #   In turn, the 'deeper_merge' library has a quirk that even though it doesn't use the ! naming convention,
-    #   it tries to modify the source array in-place. This is not cool so we need to circumvent by duplicating.
-    json = super(DEFAULT_SERIALIZE_OPTIONS.deep_dup.deeper_merge(options || {}))
+    # The intent behind this is to have a "good" default setup for serialization.
+    # We also want the caller to be able to be picky about the attributes included
+    # in the json (eg: specify an empty 'methods' to remove these attributes,
+    # or set a custom array in 'only' without getting the default ones), therefore
+    # we only use 'merge' here, which doesn't "deeply" merge into the default options.
+    json = super(DEFAULT_SERIALIZE_OPTIONS.merge(options || {}))
     # Fallback to the default 'serializable_hash' method, but always include our
     # custom 'class' attribute.
     # We can't put that in our DEFAULT_SERIALIZE_OPTIONS because the 'class'
diff --git a/WcaOnRails/spec/requests/admin_results_spec.rb b/WcaOnRails/spec/requests/admin_results_spec.rb
new file mode 100644
index 0000000000..6f27afba28
--- /dev/null
+++ b/WcaOnRails/spec/requests/admin_results_spec.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe "Admin Results" do
+  describe "Posting Check In" do
+    let!(:competition) { FactoryBot.create :competition, :with_valid_submitted_results }
+    let!(:wrt_member) { FactoryBot.create :user, :wrt_member }
+
+    it "locks a competition and returns the correct attributes" do
+      sign_in wrt_member
+      post start_posting_path, params: {
+        'competition_ids' => [competition.id],
+      }
+      expect(response).to be_successful
+      response_json = JSON.parse(response.body)
+      expect(response_json["message"]).to eq "Competitions successfully locked, go on posting!"
+      get results_posting_dashboard_path(format: :json)
+      expect(response).to be_successful
+      competitions = JSON.parse(response.body)["competitions"]
+      expect(competitions.size).to eq 1
+      expect(competitions[0]["id"]).to eq competition.id
+      expect(competitions[0]["posting_user"]["id"]).to eq wrt_member.id
+    end
+  end
+end