diff --git a/spec/controllers/users_controller_spec.rb b/spec/controllers/users_controller_spec.rb
index e6ccdf92..11620dbf 100644
--- a/spec/controllers/users_controller_spec.rb
+++ b/spec/controllers/users_controller_spec.rb
@@ -49,8 +49,14 @@
       it{ is_expected.to be_successful }
 
       it 'should return the usernames' do
+        # TODO: Remove version check once on Rails 5
+        # In Rails versions < 5, PG results when casted to_a,
+        # numeric types will get converted to string.
+        # After Rails 5, there is no typecasting, unless stated.
+        # See https://github.com/rails/rails/commit/c51f9b61ce1e167f5f58f07441adcfa117694301
+        expected_user_id = Rails.version.starts_with?('5') ? user.id : user.id.to_s
         expect(response.json[:usernames]).to match_array [{
-          'id' => user.id.to_s,
+          'id' => expected_user_id,
           'login' => user.login,
           'display_name' => user.display_name
         }]