diff --git a/.rubocop.yml b/.rubocop.yml
index 496b049..c131deb 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -20,5 +20,9 @@ Style/MethodCallWithArgsParentheses:
     - ^refute_
 Style/NumericPredicate:
   Enabled: false
+Style/StringConcatenation:
+  Enabled: false
+Style/OptionalBooleanParameter:
+  Enabled: false
 Style/WordArray:
   MinSize: 1
diff --git a/.travis.yml b/.travis.yml
index bd61a35..e3683bf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,7 +18,7 @@ addons:
       - fish
       - tmux
     update: true
-install: gem install minitest rubocop rubocop-minitest rubocop-performance
+install: gem install --no-document minitest:5.14.2 rubocop:1.0.0 rubocop-minitest:0.10.1 rubocop-performance:1.8.1
 script:
   - make test
   # LC_ALL=C to avoid escape codes in
diff --git a/test/test_go.rb b/test/test_go.rb
index 7d963ae..2861235 100755
--- a/test/test_go.rb
+++ b/test/test_go.rb
@@ -109,7 +109,7 @@ class Tmux
         class << lines
           def counts
             lazy
-              .map { |l| l.scan(%r{^. ([0-9]+)\/([0-9]+)( \(([0-9]+)\))?}) }
+              .map { |l| l.scan(%r{^. ([0-9]+)/([0-9]+)( \(([0-9]+)\))?}) }
               .reject(&:empty?)
               .first&.first&.map(&:to_i)&.values_at(0, 1, 3) || [0, 0, 0]
           end
@@ -2052,7 +2052,7 @@ module CompletionTest
     tmux.until { |lines| assert_equal 'cd /tmp/fzf-test/d55/xx', lines[-1] }
 
     # Should not match regular files (bash-only)
-    if self.class == TestBash
+    if instance_of?(TestBash)
       tmux.send_keys :Tab
       tmux.until { |lines| assert_equal 'cd /tmp/fzf-test/d55/xx', lines[-1] }
     end