diff --git a/Gemfile.lock b/Gemfile.lock
index 3e07c9ba0..cfc38dc52 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -212,7 +212,7 @@ GEM
     mime-types-data (3.2023.0218.1)
     mini_mime (1.1.2)
     mini_portile2 (2.8.4)
-    minitest (5.18.1)
+    minitest (5.19.0)
     mocha (2.1.0)
       ruby2_keywords (>= 0.0.5)
     msgpack (1.6.0)
diff --git a/test/unit/post_out_of_sync_deploys_service_test.rb b/test/unit/post_out_of_sync_deploys_service_test.rb
index b8d136728..8018fc49a 100644
--- a/test/unit/post_out_of_sync_deploys_service_test.rb
+++ b/test/unit/post_out_of_sync_deploys_service_test.rb
@@ -12,10 +12,10 @@ class PostOutOfSyncDeploysServiceTest < ActiveSupport::TestCase
              team: "#govuk-publishing-platform" }],
       }
 
-      find_service_mock = MiniTest::Mock.new
+      find_service_mock = Minitest::Mock.new
       find_service_mock.expect(:call, teams_out_of_sync_deploys)
 
-      slack_poster_mock = MiniTest::Mock.new
+      slack_poster_mock = Minitest::Mock.new
       expected_args = [
         "Hello :paw_prints:, this is your regular badgering to deploy!\n" \
         "\n" \
@@ -55,7 +55,7 @@ class PostOutOfSyncDeploysServiceTest < ActiveSupport::TestCase
       }
       FindOutOfSyncDeploysService.any_instance.stubs(:call).returns(teams_out_of_sync_deploys)
 
-      slack_poster_mock = MiniTest::Mock.new
+      slack_poster_mock = Minitest::Mock.new
       expected_message_one_args = [
         "Hello :paw_prints:, this is your regular badgering to deploy!\n" \
         "\n" \
diff --git a/test/unit/tasks/post_out_of_sync_deploys_test.rb b/test/unit/tasks/post_out_of_sync_deploys_test.rb
index 6a4f80c19..6268c8193 100644
--- a/test/unit/tasks/post_out_of_sync_deploys_test.rb
+++ b/test/unit/tasks/post_out_of_sync_deploys_test.rb
@@ -7,7 +7,7 @@ def setup
   end
 
   test "it should call PostOutOfSyncDeploysService" do
-    post_out_of_sync_deploys_service_mock = MiniTest::Mock.new
+    post_out_of_sync_deploys_service_mock = Minitest::Mock.new
     post_out_of_sync_deploys_service_mock.expect(:call, nil)
 
     PostOutOfSyncDeploysService.stub(:call, post_out_of_sync_deploys_service_mock) do