diff --git a/Library/ENV/4.3/cc b/Library/ENV/4.3/cc
index f388e00bfb..1fb6d82075 100755
--- a/Library/ENV/4.3/cc
+++ b/Library/ENV/4.3/cc
@@ -21,7 +21,7 @@ class Cmd
   end
 
   def mode
-    if @arg0 == "cpp" or @arg0 == "ld"
+    if @arg0 == "cpp" || @arg0 == "ld"
       @arg0.to_sym
     elsif @args.include? "-c"
       if @arg0 =~ /(?:c|g|clang)\+\+/
@@ -61,7 +61,7 @@ class Cmd
   end
 
   def args
-    if @args.length == 1 and @args[0] == "-v"
+    if @args.length == 1 && @args[0] == "-v"
       # Don't add linker arguments if -v passed as sole option. This stops gcc
       # -v with no other arguments from outputting a linker error. Some
       # software uses gcc -v (wrongly) to sniff the GCC version.
diff --git a/Library/ENV/scm/git b/Library/ENV/scm/git
index 06a04b7f16..0c768403ce 100755
--- a/Library/ENV/scm/git
+++ b/Library/ENV/scm/git
@@ -17,7 +17,7 @@ when "git" then %W[HOMEBREW_GIT GIT]
 when "svn" then %W[HOMEBREW_SVN]
 else []
 end.each do |key|
-  exec ENV[key], *ARGV if ENV[key] and File.executable? ENV[key]
+  exec ENV[key], *ARGV if ENV[key] && File.executable?(ENV[key])
 end
 
 brew_version = File.expand_path("#{D}/../../../bin/#{F}")
diff --git a/Library/Homebrew/bottles.rb b/Library/Homebrew/bottles.rb
index 5b0073d3b2..2686f2468d 100644
--- a/Library/Homebrew/bottles.rb
+++ b/Library/Homebrew/bottles.rb
@@ -63,12 +63,12 @@ end
 
 class Bintray
   def self.package(formula_name)
-    formula_name.to_s.gsub "+", "x"
+    formula_name.to_s.tr("+", "x")
   end
 
   def self.repository(tap = nil)
     return "bottles" if tap.nil? || tap == "Homebrew/homebrew"
-    "bottles-#{tap.sub(/^homebrew\/(homebrew-)?/i, "")}"
+    "bottles-#{tap.sub(%r{^homebrew/(homebrew-)?}i, "")}"
   end
 end
 
diff --git a/Library/Homebrew/caveats.rb b/Library/Homebrew/caveats.rb
index 59e15ebbc0..3eab3722b9 100644
--- a/Library/Homebrew/caveats.rb
+++ b/Library/Homebrew/caveats.rb
@@ -149,8 +149,11 @@ class Caveats
   def plist_caveats
     s = []
     if f.plist || (keg && keg.plist_installed?)
-      destination = f.plist_startup ? "/Library/LaunchDaemons" \
-                                    : "~/Library/LaunchAgents"
+      destination = if f.plist_startup
+        "/Library/LaunchDaemons"
+      else
+        "~/Library/LaunchAgents"
+      end
 
       plist_filename = if f.plist
         f.plist_path.basename
diff --git a/Library/Homebrew/cmd/aspell-dictionaries.rb b/Library/Homebrew/cmd/aspell-dictionaries.rb
index f610ecfbd6..754b6614ed 100644
--- a/Library/Homebrew/cmd/aspell-dictionaries.rb
+++ b/Library/Homebrew/cmd/aspell-dictionaries.rb
@@ -16,7 +16,7 @@ module Homebrew
         fields = line.split('"')
         lang = fields[1]
         path = fields[3]
-        lang.gsub!("-", "_")
+        lang.tr!("-", "_")
         languages[lang] = path
       end
     end
diff --git a/Library/Homebrew/cmd/audit.rb b/Library/Homebrew/cmd/audit.rb
index 7390b8a86f..84a93859f9 100644
--- a/Library/Homebrew/cmd/audit.rb
+++ b/Library/Homebrew/cmd/audit.rb
@@ -360,7 +360,7 @@ class FormulaAuditor
       EOS
     end
 
-    if desc =~ %r[([Cc]ommand ?line)]
+    if desc =~ /([Cc]ommand ?line)/
       problem "Description should use \"command-line\" instead of \"#{$1}\""
     end
   end
diff --git a/Library/Homebrew/cmd/list.rb b/Library/Homebrew/cmd/list.rb
index 53985d1135..068f268355 100644
--- a/Library/Homebrew/cmd/list.rb
+++ b/Library/Homebrew/cmd/list.rb
@@ -136,7 +136,7 @@ class PrettyListing
     root.children.sort.each do |pn|
       if pn.directory?
         dirs << pn
-      elsif block_given? and yield pn
+      elsif block_given? && yield(pn)
         puts pn
         other = "other "
       else
diff --git a/Library/Homebrew/cmd/test-bot.rb b/Library/Homebrew/cmd/test-bot.rb
index 8e9e3c239b..6dcd301aab 100644
--- a/Library/Homebrew/cmd/test-bot.rb
+++ b/Library/Homebrew/cmd/test-bot.rb
@@ -793,7 +793,7 @@ module Homebrew
       bottle_args << "--tap=#{tap}" if tap
       safe_system "brew", "bottle", *bottle_args
 
-      remote_repo = tap ? tap.gsub("/", "-") : "homebrew"
+      remote_repo = tap ? tap.tr("/", "-") : "homebrew"
 
       remote = "git@github.com:BrewTestBot/#{remote_repo}.git"
       tag = pr ? "pr-#{pr}" : "testing-#{number}"
diff --git a/Library/Homebrew/config.rb b/Library/Homebrew/config.rb
index bd8e3e53c8..57cf19283d 100644
--- a/Library/Homebrew/config.rb
+++ b/Library/Homebrew/config.rb
@@ -5,7 +5,7 @@ def cache
     # we do this for historic reasons, however the cache *should* be the same
     # directory whichever user is used and whatever instance of brew is executed
     home_cache = Pathname.new("~/Library/Caches/Homebrew").expand_path
-    if home_cache.directory? and home_cache.writable_real?
+    if home_cache.directory? && home_cache.writable_real?
       home_cache
     else
       Pathname.new("/Library/Caches/Homebrew").extend Module.new {
diff --git a/Library/Homebrew/debrew.rb b/Library/Homebrew/debrew.rb
index 3f21094be4..7b1b507359 100644
--- a/Library/Homebrew/debrew.rb
+++ b/Library/Homebrew/debrew.rb
@@ -53,7 +53,7 @@ module Debrew
         menu.entries.each_with_index { |e, i| puts "#{i+1}. #{e.name}" }
         print menu.prompt unless menu.prompt.nil?
 
-        input = $stdin.gets or exit
+        input = $stdin.gets || exit
         input.chomp!
 
         i = input.to_i
diff --git a/Library/Homebrew/extend/ENV/super.rb b/Library/Homebrew/extend/ENV/super.rb
index 9116029194..a5892d122b 100644
--- a/Library/Homebrew/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/ENV/super.rb
@@ -121,7 +121,7 @@ module Superenv
     when "gcc-4.2"
       begin
         apple_gcc42 = Formulary.factory("apple-gcc42")
-       rescue FormulaUnavailableError
+      rescue FormulaUnavailableError
       end
       paths << apple_gcc42.opt_bin.to_s if apple_gcc42
     when GNU_GCC_REGEXP
diff --git a/Library/Homebrew/formula_cellar_checks.rb b/Library/Homebrew/formula_cellar_checks.rb
index 0c62687acc..071b3f4ddd 100644
--- a/Library/Homebrew/formula_cellar_checks.rb
+++ b/Library/Homebrew/formula_cellar_checks.rb
@@ -152,7 +152,7 @@ module FormulaCellarChecks
       object files were linked against system openssl
       These object files were linked against the deprecated system OpenSSL.
       Adding `depends_on "openssl"` to the formula may help.
-        #{system_openssl  * "\n        "}
+        #{system_openssl * "\n        "}
     EOS
   end
 
diff --git a/Library/Homebrew/formulary.rb b/Library/Homebrew/formulary.rb
index 9999ce8dd2..b684519c64 100644
--- a/Library/Homebrew/formulary.rb
+++ b/Library/Homebrew/formulary.rb
@@ -43,7 +43,7 @@ class Formulary
   def self.class_s(name)
     class_name = name.capitalize
     class_name.gsub!(/[-_.\s]([a-zA-Z0-9])/) { $1.upcase }
-    class_name.gsub!("+", "x")
+    class_name.tr!("+", "x")
     class_name
   end
 
diff --git a/Library/Homebrew/os/mac/hardware.rb b/Library/Homebrew/os/mac/hardware.rb
index 11cf0142ae..db4fe58758 100644
--- a/Library/Homebrew/os/mac/hardware.rb
+++ b/Library/Homebrew/os/mac/hardware.rb
@@ -62,7 +62,7 @@ module MacCPUs
       when 100
         # This is the only 64-bit PPC CPU type, so it's useful
         # to distinguish in `brew config` output and in bottle tags
-        MacOS.prefer_64_bit? ? :g5_64 : :g5  # PowerPC 970
+        MacOS.prefer_64_bit? ? :g5_64 : :g5 # PowerPC 970
       else
         :dunno
       end
diff --git a/Library/Homebrew/resource.rb b/Library/Homebrew/resource.rb
index 0c3184180f..202b457744 100644
--- a/Library/Homebrew/resource.rb
+++ b/Library/Homebrew/resource.rb
@@ -57,7 +57,7 @@ class Resource
   # to be used as resource names without confusing software that
   # interacts with download_name, e.g. github.com/foo/bar
   def escaped_name
-    name.gsub("/", "-")
+    name.tr("/", "-")
   end
 
   def download_name
diff --git a/Library/Homebrew/sandbox.rb b/Library/Homebrew/sandbox.rb
index 835ed8a25d..0f4881b416 100644
--- a/Library/Homebrew/sandbox.rb
+++ b/Library/Homebrew/sandbox.rb
@@ -79,7 +79,6 @@ class Sandbox
   end
 
   def exec(*args)
-
     seatbelt = Tempfile.new(["homebrew", ".sb"], HOMEBREW_TEMP)
     seatbelt.write(@profile.dump)
     seatbelt.close
@@ -105,7 +104,6 @@ class Sandbox
       ]
       quiet_system "syslog #{syslog_args * " "} | grep deny > #{@log}"
     end
-
   end
 
   private
diff --git a/Library/Homebrew/test/test_inreplace.rb b/Library/Homebrew/test/test_inreplace.rb
index 7b0dfe64d1..d9c4c1ab7b 100644
--- a/Library/Homebrew/test/test_inreplace.rb
+++ b/Library/Homebrew/test/test_inreplace.rb
@@ -85,7 +85,7 @@ class InreplaceTest < Homebrew::TestCase
     s.sub!("f", "b")
     assert_equal "boo", s
 
-    s.gsub!("o", "e")
+    s.tr!("o", "e")
     assert_equal "bee", s
   end
 
@@ -99,7 +99,7 @@ class InreplaceTest < Homebrew::TestCase
     end
 
     assert_raises(Utils::InreplaceError) do
-      inreplace("test") { |s| s.gsub! "d", "f" }
+      inreplace("test") { |s| s.tr!("d", "f") }
     end
 
     assert_raises(Utils::InreplaceError) do
diff --git a/Library/Homebrew/version.rb b/Library/Homebrew/version.rb
index 5c9030cd70..d3f0417b01 100644
--- a/Library/Homebrew/version.rb
+++ b/Library/Homebrew/version.rb
@@ -299,7 +299,7 @@ class Version
 
     # e.g. boost_1_39_0
     m = /((?:\d+_)+\d+)$/.match(stem)
-    return m.captures.first.gsub("_", ".") unless m.nil?
+    return m.captures.first.tr("_", ".") unless m.nil?
 
     # e.g. foobar-4.5.1-1
     # e.g. unrtf_0.20.4-1