diff --git a/app/controllers/concerns/boards_responses.rb b/app/controllers/concerns/boards_responses.rb
index ce2740147f7..128409a2eef 100644
--- a/app/controllers/concerns/boards_responses.rb
+++ b/app/controllers/concerns/boards_responses.rb
@@ -69,7 +69,7 @@ module BoardsResponses
   end
 
   def serialize_as_json(resource)
-    serializer.represent(resource)
+    serializer.represent(resource).to_json
   end
 
   def respond_with(resource)
diff --git a/changelogs/unreleased/ce-3861-use-serializers-for-project-group-boards.yml b/changelogs/unreleased/3861-use-serializers-for-project-group-boards.yml
similarity index 100%
rename from changelogs/unreleased/ce-3861-use-serializers-for-project-group-boards.yml
rename to changelogs/unreleased/3861-use-serializers-for-project-group-boards.yml
diff --git a/spec/controllers/concerns/boards_responses_spec.rb b/spec/controllers/concerns/boards_responses_spec.rb
index 1c837fe8755..c080ddf896f 100644
--- a/spec/controllers/concerns/boards_responses_spec.rb
+++ b/spec/controllers/concerns/boards_responses_spec.rb
@@ -15,9 +15,9 @@ describe BoardsResponses do
     let!(:board) { create(:board) }
 
     it 'serializes properly' do
-      expected = { id: board.id }
+      expected = { "id" => board.id }
 
-      expect(subject.serialize_as_json(board).to_h).to include(expected)
+      expect(JSON.parse(subject.serialize_as_json(board))).to include(expected)
     end
   end
 end