diff --git a/Library/Homebrew/cmd/readall.rb b/Library/Homebrew/cmd/readall.rb
index 3468d0036f..7c64d8eb09 100644
--- a/Library/Homebrew/cmd/readall.rb
+++ b/Library/Homebrew/cmd/readall.rb
@@ -32,7 +32,7 @@ module Homebrew
 
     if args.syntax? && args.no_named?
       scan_files = "#{HOMEBREW_LIBRARY_PATH}/**/*.rb"
-      ruby_files = Dir.glob(scan_files).reject { |file| file =~ %r{/(vendor)/} }
+      ruby_files = Dir.glob(scan_files).grep_v(%r{/(vendor)/})
 
       Homebrew.failed = true unless Readall.valid_ruby_syntax?(ruby_files)
     end
diff --git a/Library/Homebrew/dev-cmd/tests.rb b/Library/Homebrew/dev-cmd/tests.rb
index 63f8d4dc2e..010c7c2f78 100644
--- a/Library/Homebrew/dev-cmd/tests.rb
+++ b/Library/Homebrew/dev-cmd/tests.rb
@@ -168,12 +168,12 @@ module Homebrew
 
       unless OS.mac?
         bundle_args << "--tag" << "~needs_macos" << "--tag" << "~cask"
-        files = files.reject { |p| p =~ %r{^test/(os/mac|cask)(/.*|_spec\.rb)$} }
+        files = files.grep_v(%r{^test/(os/mac|cask)(/.*|_spec\.rb)$})
       end
 
       unless OS.linux?
         bundle_args << "--tag" << "~needs_linux"
-        files = files.reject { |p| p =~ %r{^test/os/linux(/.*|_spec\.rb)$} }
+        files = files.grep_v(%r{^test/os/linux(/.*|_spec\.rb)$})
       end
 
       puts "Randomized with seed #{seed}"
diff --git a/Library/Homebrew/extend/ENV/super.rb b/Library/Homebrew/extend/ENV/super.rb
index acd68e8358..40ef42a4b4 100644
--- a/Library/Homebrew/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/ENV/super.rb
@@ -217,12 +217,12 @@ module Superenv
       rescue FormulaUnavailableError
         nil
       else
-        paths << f.opt_lib/"gcc"/f.version.major if f.any_version_installed?
+        paths << (f.opt_lib/"gcc"/f.version.major) if f.any_version_installed?
       end
     end
 
     paths << keg_only_deps.map(&:opt_lib)
-    paths << HOMEBREW_PREFIX/"lib"
+    paths << (HOMEBREW_PREFIX/"lib")
 
     paths += homebrew_extra_library_paths
     PATH.new(paths).existing
diff --git a/Library/Homebrew/extend/os/mac/keg_relocate.rb b/Library/Homebrew/extend/os/mac/keg_relocate.rb
index a0abdb0ab9..e190ccaec2 100644
--- a/Library/Homebrew/extend/os/mac/keg_relocate.rb
+++ b/Library/Homebrew/extend/os/mac/keg_relocate.rb
@@ -95,7 +95,7 @@ class Keg
     links = file.method(linkage_type)
                 .call
                 .uniq
-                .reject { |fn| fn =~ /^@(loader_|executable_|r)path/ }
+                .grep_v(/^@(loader_|executable_|r)path/)
     links.each(&block)
   end
 
diff --git a/Library/Homebrew/rubocops/bottle.rb b/Library/Homebrew/rubocops/bottle.rb
index e1e4cd01c5..fd69556cb6 100644
--- a/Library/Homebrew/rubocops/bottle.rb
+++ b/Library/Homebrew/rubocops/bottle.rb
@@ -82,7 +82,7 @@ module RuboCop
 
             offending_node(hash)
             problem "Align bottle tags" do |corrector|
-              new_line = " " * (max_tag_column - tag_column) + hash.source
+              new_line = (" " * (max_tag_column - tag_column)) + hash.source
               corrector.replace(hash.source_range, new_line)
             end
           end
@@ -118,7 +118,7 @@ module RuboCop
 
             offending_node(hash)
             problem "Align bottle digests" do |corrector|
-              new_line = " " * (max_digest_column - digest_column) + hash.source
+              new_line = (" " * (max_digest_column - digest_column)) + hash.source
               corrector.replace(hash.source_range, new_line)
             end
           end
diff --git a/Library/Homebrew/tap.rb b/Library/Homebrew/tap.rb
index 6aba948771..23b61b2c91 100644
--- a/Library/Homebrew/tap.rb
+++ b/Library/Homebrew/tap.rb
@@ -416,7 +416,7 @@ class Tap
 
   # Path to the directory of all {Formula} files for this {Tap}.
   def formula_dir
-    @formula_dir ||= potential_formula_dirs.find(&:directory?) || path/"Formula"
+    @formula_dir ||= potential_formula_dirs.find(&:directory?) || (path/"Formula")
   end
 
   def potential_formula_dirs
diff --git a/Library/Homebrew/test/cask/cmd/uninstall_spec.rb b/Library/Homebrew/test/cask/cmd/uninstall_spec.rb
index 80578667e7..527675b6fa 100644
--- a/Library/Homebrew/test/cask/cmd/uninstall_spec.rb
+++ b/Library/Homebrew/test/cask/cmd/uninstall_spec.rb
@@ -138,7 +138,7 @@ describe Cask::Cmd::Uninstall, :cask do
 
       saved_caskfile.dirname.mkpath
 
-      IO.write saved_caskfile, <<~RUBY
+      File.write saved_caskfile, <<~RUBY
         cask 'ive-been-renamed' do
           version :latest
 
diff --git a/Library/Homebrew/test/cleanup_spec.rb b/Library/Homebrew/test/cleanup_spec.rb
index 0f98f539db..477de25fcd 100644
--- a/Library/Homebrew/test/cleanup_spec.rb
+++ b/Library/Homebrew/test/cleanup_spec.rb
@@ -315,8 +315,8 @@ describe Homebrew::Cleanup do
     it "cleans up VCS checkout directories with modified time < prune time" do
       foo = (HOMEBREW_CACHE/"--foo")
       foo.mkpath
-      allow_any_instance_of(Pathname).to receive(:ctime).and_return(Time.now - 2 * 60 * 60 * 24)
-      allow_any_instance_of(Pathname).to receive(:mtime).and_return(Time.now - 2 * 60 * 60 * 24)
+      allow_any_instance_of(Pathname).to receive(:ctime).and_return(Time.now - (2 * 60 * 60 * 24))
+      allow_any_instance_of(Pathname).to receive(:mtime).and_return(Time.now - (2 * 60 * 60 * 24))
       described_class.new(days: 1).cleanup_cache
       expect(foo).not_to exist
     end
diff --git a/Library/Homebrew/test/support/fixtures/cask/Casks/with-uninstall-script-app.rb b/Library/Homebrew/test/support/fixtures/cask/Casks/with-uninstall-script-app.rb
index 1b768b25da..22735487d2 100644
--- a/Library/Homebrew/test/support/fixtures/cask/Casks/with-uninstall-script-app.rb
+++ b/Library/Homebrew/test/support/fixtures/cask/Casks/with-uninstall-script-app.rb
@@ -8,7 +8,7 @@ cask "with-uninstall-script-app" do
   app "MyFancyApp/MyFancyApp.app"
 
   postflight do
-    IO.write "#{appdir}/MyFancyApp.app/uninstall.sh", <<~SH
+    File.write "#{appdir}/MyFancyApp.app/uninstall.sh", <<~SH
       #!/bin/sh
       /bin/rm -r "#{appdir}/MyFancyApp.app"
     SH
diff --git a/Library/Homebrew/test/support/fixtures/cask/Casks/with-uninstall-script-user-relative.rb b/Library/Homebrew/test/support/fixtures/cask/Casks/with-uninstall-script-user-relative.rb
index fbe786abb3..1908663b4c 100644
--- a/Library/Homebrew/test/support/fixtures/cask/Casks/with-uninstall-script-user-relative.rb
+++ b/Library/Homebrew/test/support/fixtures/cask/Casks/with-uninstall-script-user-relative.rb
@@ -8,7 +8,7 @@ cask "with-uninstall-script-user-relative" do
   app "MyFancyApp/MyFancyApp.app", target: "~/MyFancyApp.app"
 
   postflight do
-    IO.write "#{ENV["HOME"]}/MyFancyApp.app/uninstall.sh", <<~SH
+    File.write "#{ENV["HOME"]}/MyFancyApp.app/uninstall.sh", <<~SH
       #!/bin/sh
       /bin/rm -r "#{ENV["HOME"]}/MyFancyApp.app"
     SH
diff --git a/Library/Homebrew/test/utils_spec.rb b/Library/Homebrew/test/utils_spec.rb
index c54a886574..f92d0bbcde 100644
--- a/Library/Homebrew/test/utils_spec.rb
+++ b/Library/Homebrew/test/utils_spec.rb
@@ -95,7 +95,7 @@ describe "globally-scoped helper methods" do
     let(:shell) { dir/"myshell" }
 
     it "starts an interactive shell session" do
-      IO.write shell, <<~SH
+      File.write shell, <<~SH
         #!/bin/sh
         echo called > "#{dir}/called"
       SH
diff --git a/Library/Homebrew/utils/formatter.rb b/Library/Homebrew/utils/formatter.rb
index 7835e93f28..1d88df0540 100644
--- a/Library/Homebrew/utils/formatter.rb
+++ b/Library/Homebrew/utils/formatter.rb
@@ -98,7 +98,7 @@ module Formatter
     rows = (objects.count + cols - 1) / cols
     cols = (objects.count + rows - 1) / rows # avoid empty trailing columns
 
-    col_width = (console_width + gap_size) / cols - gap_size
+    col_width = ((console_width + gap_size) / cols) - gap_size
 
     gap_string = "".rjust(gap_size)
 
diff --git a/Library/Homebrew/utils/repology.rb b/Library/Homebrew/utils/repology.rb
index 32f817c420..9250acc4a6 100644
--- a/Library/Homebrew/utils/repology.rb
+++ b/Library/Homebrew/utils/repology.rb
@@ -65,7 +65,7 @@ module Repology
       last_package = response.keys.last
 
       page_no += 1
-      break if limit && outdated_packages.size >= limit || response.size <= 1
+      break if (limit && outdated_packages.size >= limit) || response.size <= 1
     end
 
     puts "#{outdated_packages.size} outdated #{package_term.pluralize(outdated_packages.size)} found"