diff --git a/.expeditor/buildkite/verify.sh b/.expeditor/buildkite/verify.sh
index 01982b79..d55ec1e5 100755
--- a/.expeditor/buildkite/verify.sh
+++ b/.expeditor/buildkite/verify.sh
@@ -7,6 +7,7 @@ bundle --version
 
 echo "--- bundle install"
 bundle config --local path vendor/bundle
+bundle config --local without integration tools
 bundle install --jobs=7 --retry=3
 
 echo "+++ bundle exec rake"
diff --git a/Gemfile b/Gemfile
index cb846477..f4f355c9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,11 +1,6 @@
 source "https://rubygems.org"
 gemspec name: "train"
 
-if Gem.ruby_version.to_s.start_with?("2.5")
-  # 16.7.23 required ruby 2.6+
-  gem "chef-utils", "< 16.7.23" # TODO: remove when we drop ruby 2.5
-end
-
 group :test do
   gem "minitest", "~> 5.8"
   gem "rake", "~> 13.0"
@@ -20,7 +15,9 @@ group :test do
   # but it's close enough to show the gempath handler can find a plugin
   # See test/unit/
   gem "train-test-fixture", path: "test/fixtures/plugins/train-test-fixture"
-  gem "mocha", "~> 1.1"
+  # Mocha ~1.1 is incompatible with minitest v5.19 and later
+  # More on the issue: https://github.com/freerange/mocha/issues/614
+  gem "mocha", "~> 2"
 end
 
 if Gem.ruby_version >= Gem::Version.new("2.7.0")
diff --git a/test/unit/transports/ssh_test.rb b/test/unit/transports/ssh_test.rb
index 0d095f9d..51917416 100644
--- a/test/unit/transports/ssh_test.rb
+++ b/test/unit/transports/ssh_test.rb
@@ -215,7 +215,8 @@
     end
 
     it "sets up a proxy when ssh proxy command is specified" do
-      mock = MiniTest::Mock.new
+      mock = Minitest::Mock.new
+
       mock.expect(:call, true) do |hostname, username, options|
         options[:proxy].is_a?(Net::SSH::Proxy::Command) &&
           "ssh root@127.0.0.1 -W %h:%p" == options[:proxy].command_line_template
@@ -384,7 +385,7 @@
       end
 
       it "sets up a proxy when ssh proxy command is specified" do
-        mock = MiniTest::Mock.new
+        mock = Minitest::Mock.new
         mock.expect(:call, true) do |hostname, username, options|
           options[:proxy].is_a?(Net::SSH::Proxy::Command) &&
             "ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o LogLevel=ERROR -o ForwardAgent=no -o IdentitiesOnly=yes -i #{conf[:key_files]} root@bastion_dummy -p 22 -W %h:%p" == options[:proxy].command_line_template