diff --git a/Library/Homebrew/locale.rb b/Library/Homebrew/locale.rb
index 854e1df8f2..acb9f81c5f 100644
--- a/Library/Homebrew/locale.rb
+++ b/Library/Homebrew/locale.rb
@@ -13,7 +13,7 @@ class Locale
   def self.parse(string)
     string = string.to_s
 
-    raise ParserError, "'#{string}' cannot be parsed to a #{self}" if !LOCALE_REGEX.match?(string)
+    raise ParserError, "'#{string}' cannot be parsed to a #{self}" unless LOCALE_REGEX.match?(string)
 
     scan = proc do |regex|
       string.scan(/(?:\-|^)(#{regex})(?:\-|$)/).flatten.first
diff --git a/Library/Homebrew/rubocops/cask/homepage_url_trailing_slash.rb b/Library/Homebrew/rubocops/cask/homepage_url_trailing_slash.rb
index 9f00a07d84..bf39a191ea 100644
--- a/Library/Homebrew/rubocops/cask/homepage_url_trailing_slash.rb
+++ b/Library/Homebrew/rubocops/cask/homepage_url_trailing_slash.rb
@@ -17,7 +17,7 @@ module RuboCop
           url_node = stanza.stanza_node.first_argument
           url = url_node.str_content
 
-          return if !%r{^.+://[^/]+$}.match?(url)
+          return unless %r{^.+://[^/]+$}.match?(url)
 
           add_offense(url_node, location: :expression,
                                 message:  format(MSG_NO_SLASH, url: url))
diff --git a/Library/Homebrew/rubocops/patches.rb b/Library/Homebrew/rubocops/patches.rb
index 03f2e72997..5bbb578e16 100644
--- a/Library/Homebrew/rubocops/patches.rb
+++ b/Library/Homebrew/rubocops/patches.rb
@@ -30,7 +30,7 @@ module RuboCop
           patch_url = string_content(patch)
           gh_patch_param_pattern = %r{https?://github\.com/.+/.+/(?:commit|pull)/[a-fA-F0-9]*.(?:patch|diff)}
           if regex_match_group(patch, gh_patch_param_pattern)
-            if !/\?full_index=\w+$/.match?(patch_url)
+            unless /\?full_index=\w+$/.match?(patch_url)
               problem <<~EOS
                 GitHub patches should use the full_index parameter:
                   #{patch_url}?full_index=1
@@ -43,7 +43,7 @@ module RuboCop
                                             %r{gist\.github\.com/.+/raw},
                                             %r{gist\.githubusercontent\.com/.+/raw}])
           if regex_match_group(patch, gh_patch_patterns)
-            if !/[a-fA-F0-9]{40}/.match?(patch_url)
+            unless /[a-fA-F0-9]{40}/.match?(patch_url)
               problem <<~EOS.chomp
                 GitHub/Gist patches should specify a revision:
                   #{patch_url}