diff --git a/Library/Homebrew/cmd/doctor.rb b/Library/Homebrew/cmd/doctor.rb
index 18af768b47..c1921c9756 100644
--- a/Library/Homebrew/cmd/doctor.rb
+++ b/Library/Homebrew/cmd/doctor.rb
@@ -42,7 +42,7 @@ class Checks
 
 ############# HELPERS
   def paths
-    @paths ||= ENV['PATH'].split(':').collect do |p|
+    @paths ||= ENV['PATH'].split(File::PATH_SEPARATOR).collect do |p|
       begin
         File.expand_path(p).chomp('/')
       rescue ArgumentError
@@ -68,7 +68,7 @@ class Checks
 # Sorry for the lack of an indent here, the diff would have been unreadable.
 # See https://github.com/mxcl/homebrew/pull/9986
 def check_path_for_trailing_slashes
-  bad_paths = ENV['PATH'].split(':').select { |p| p[-1..-1] == '/' }
+  bad_paths = ENV['PATH'].split(File::PATH_SEPARATOR).select { |p| p[-1..-1] == '/' }
   return if bad_paths.empty?
   s = <<-EOS.undent
     Some directories in your path end in a slash.
diff --git a/Library/Homebrew/cmd/sh.rb b/Library/Homebrew/cmd/sh.rb
index a1ff30dfcd..82fcc968d8 100644
--- a/Library/Homebrew/cmd/sh.rb
+++ b/Library/Homebrew/cmd/sh.rb
@@ -12,7 +12,7 @@ module Homebrew extend self
     ENV.setup_build_environment
     if superenv?
       # superenv stopped adding brew's bin but generally user's will want it
-      ENV['PATH'] = ENV['PATH'].split(':').insert(1, "#{HOMEBREW_PREFIX}/bin").join(':')
+      ENV['PATH'] = ENV['PATH'].split(File::PATH_SEPARATOR).insert(1, "#{HOMEBREW_PREFIX}/bin").join(File::PATH_SEPARATOR)
     end
     ENV['PS1'] = 'brew \[\033[1;32m\]\w\[\033[0m\]$ '
     ENV['VERBOSE'] = '1'
diff --git a/Library/Homebrew/extend/ENV/shared.rb b/Library/Homebrew/extend/ENV/shared.rb
index 0b5fee954d..5ceecd8440 100644
--- a/Library/Homebrew/extend/ENV/shared.rb
+++ b/Library/Homebrew/extend/ENV/shared.rb
@@ -36,7 +36,7 @@ module SharedEnvExtension
     end
   end
   def prepend_path key, path
-    prepend key, path, ':' if File.directory? path
+    prepend key, path, File::PATH_SEPARATOR if File.directory? path
   end
   def remove keys, value
     Array(keys).each do |key|
@@ -65,9 +65,9 @@ module SharedEnvExtension
 
   def userpaths!
     paths = ORIGINAL_PATHS.map { |p| p.realpath.to_s rescue nil } - %w{/usr/X11/bin /opt/X11/bin}
-    self['PATH'] = paths.unshift(*self['PATH'].split(":")).uniq.join(":")
+    self['PATH'] = paths.unshift(*self['PATH'].split(PATH_SEPARATOR)).uniq.join(File::PATH_SEPARATOR)
     # XXX hot fix to prefer brewed stuff (e.g. python) over /usr/bin.
-    prepend 'PATH', HOMEBREW_PREFIX/'bin', ':'
+    prepend 'PATH', HOMEBREW_PREFIX/'bin', File::PATH_SEPARATOR
   end
 
   def fortran
diff --git a/Library/Homebrew/extend/ENV/std.rb b/Library/Homebrew/extend/ENV/std.rb
index 24007a46d3..caf0471e86 100644
--- a/Library/Homebrew/extend/ENV/std.rb
+++ b/Library/Homebrew/extend/ENV/std.rb
@@ -72,9 +72,9 @@ module Stdenv
     # For Xcode 4.3 (*without* the "Command Line Tools for Xcode") compiler and tools inside of Xcode:
     if not MacOS::CLT.installed? and MacOS::Xcode.installed? and MacOS::Xcode.version >= "4.3"
       # Some tools (clang, etc.) are in the xctoolchain dir of Xcode
-      append 'PATH', "#{MacOS.xctoolchain_path}/usr/bin", ":" if MacOS.xctoolchain_path
+      append 'PATH', "#{MacOS.xctoolchain_path}/usr/bin", File::PATH_SEPARATOR if MacOS.xctoolchain_path
       # Others are now at /Applications/Xcode.app/Contents/Developer/usr/bin
-      append 'PATH', "#{MacOS.dev_tools_path}", ":"
+      append 'PATH', "#{MacOS.dev_tools_path}", File::PATH_SEPARATOR
     end
   end
 
@@ -84,7 +84,7 @@ module Stdenv
     paths << HOMEBREW_PREFIX/'share/pkgconfig'
     paths << HOMEBREW_REPOSITORY/"Library/ENV/pkgconfig/#{MacOS.version}"
     paths << '/usr/lib/pkgconfig'
-    paths.select { |d| File.directory? d }.join(':')
+    paths.select { |d| File.directory? d }.join(File::PATH_SEPARATOR)
   end
 
   def deparallelize
@@ -217,15 +217,15 @@ module Stdenv
       # Extra setup to support Xcode 4.3+ without CLT.
       self['SDKROOT'] = sdk
       # Tell clang/gcc where system include's are:
-      append 'CPATH', "#{sdk}/usr/include", ":"
+      append 'CPATH', "#{sdk}/usr/include", File::PATH_SEPARATOR
       # The -isysroot is needed, too, because of the Frameworks
       append_to_cflags "-isysroot #{sdk}"
       append 'CPPFLAGS', "-isysroot #{sdk}"
       # And the linker needs to find sdk/usr/lib
       append 'LDFLAGS', "-isysroot #{sdk}"
       # Needed to build cmake itself and perhaps some cmake projects:
-      append 'CMAKE_PREFIX_PATH', "#{sdk}/usr", ':'
-      append 'CMAKE_FRAMEWORK_PATH', "#{sdk}/System/Library/Frameworks", ':'
+      append 'CMAKE_PREFIX_PATH', "#{sdk}/usr", File::PATH_SEPARATOR
+      append 'CMAKE_FRAMEWORK_PATH', "#{sdk}/System/Library/Frameworks", File::PATH_SEPARATOR
     end
   end
 
@@ -250,24 +250,24 @@ module Stdenv
 
   def x11
     # There are some config scripts here that should go in the PATH
-    append 'PATH', MacOS::X11.bin, ':'
+    append 'PATH', MacOS::X11.bin, File::PATH_SEPARATOR
 
     # Append these to PKG_CONFIG_LIBDIR so they are searched
     # *after* our own pkgconfig directories, as we dupe some of the
     # libs in XQuartz.
-    append 'PKG_CONFIG_LIBDIR', MacOS::X11.lib/'pkgconfig', ':'
-    append 'PKG_CONFIG_LIBDIR', MacOS::X11.share/'pkgconfig', ':'
+    append 'PKG_CONFIG_LIBDIR', MacOS::X11.lib/'pkgconfig', File::PATH_SEPARATOR
+    append 'PKG_CONFIG_LIBDIR', MacOS::X11.share/'pkgconfig', File::PATH_SEPARATOR
 
     append 'LDFLAGS', "-L#{MacOS::X11.lib}"
-    append 'CMAKE_PREFIX_PATH', MacOS::X11.prefix, ':'
-    append 'CMAKE_INCLUDE_PATH', MacOS::X11.include, ':'
+    append 'CMAKE_PREFIX_PATH', MacOS::X11.prefix, File::PATH_SEPARATOR
+    append 'CMAKE_INCLUDE_PATH', MacOS::X11.include, File::PATH_SEPARATOR
 
     append 'CPPFLAGS', "-I#{MacOS::X11.include}"
 
-    append 'ACLOCAL_PATH', MacOS::X11.share/'aclocal', ':'
+    append 'ACLOCAL_PATH', MacOS::X11.share/'aclocal', File::PATH_SEPARATOR
 
     unless MacOS::CLT.installed?
-      append 'CMAKE_PREFIX_PATH', MacOS.sdk_path/'usr/X11', ':'
+      append 'CMAKE_PREFIX_PATH', MacOS.sdk_path/'usr/X11', File::PATH_SEPARATOR
       append 'CPPFLAGS', "-I#{MacOS::X11.include}/freetype2"
       append 'CFLAGS', "-I#{MacOS::X11.include}"
     end
diff --git a/Library/Homebrew/extend/ENV/super.rb b/Library/Homebrew/extend/ENV/super.rb
index 5bfa34437c..84247b2fdb 100644
--- a/Library/Homebrew/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/ENV/super.rb
@@ -96,7 +96,7 @@ module Superenv
     # so xcrun may not be able to find it
     if self['HOMEBREW_CC'] == 'gcc-4.2'
       apple_gcc42 = Formula.factory('apple-gcc42') rescue nil
-      append('PATH', apple_gcc42.opt_prefix/'bin', ':') if apple_gcc42
+      append('PATH', apple_gcc42.opt_prefix/'bin', File::PATH_SEPARATOR) if apple_gcc42
     end
   end
 
@@ -303,6 +303,6 @@ end
 
 class Array
   def to_path_s
-    map(&:to_s).uniq.select{|s| File.directory? s }.join(':').chuzzle
+    map(&:to_s).uniq.select{|s| File.directory? s }.join(File::PATH_SEPARATOR).chuzzle
   end
 end
diff --git a/Library/Homebrew/global.rb b/Library/Homebrew/global.rb
index dea7d25915..18934c6ca8 100644
--- a/Library/Homebrew/global.rb
+++ b/Library/Homebrew/global.rb
@@ -98,7 +98,7 @@ HOMEBREW_PULL_OR_COMMIT_URL_REGEX = 'https:\/\/github.com\/(\w+)\/homebrew(-\w+)
 
 require 'compat' unless ARGV.include? "--no-compat" or ENV['HOMEBREW_NO_COMPAT']
 
-ORIGINAL_PATHS = ENV['PATH'].split(':').map{ |p| Pathname.new(p).expand_path rescue nil }.compact.freeze
+ORIGINAL_PATHS = ENV['PATH'].split(File::PATH_SEPARATOR).map{ |p| Pathname.new(p).expand_path rescue nil }.compact.freeze
 
 SUDO_BAD_ERRMSG = <<-EOS.undent
   You can use brew with sudo, but only if the brew executable is owned by root.
diff --git a/Library/Homebrew/python_helper.rb b/Library/Homebrew/python_helper.rb
index cb2e5d9896..30eddb7c07 100644
--- a/Library/Homebrew/python_helper.rb
+++ b/Library/Homebrew/python_helper.rb
@@ -62,11 +62,11 @@ def python_helper(options={:allowed_major_versions => [2, 3]}, &block)
       # so that lib points to the HOMEBREW_PREFIX/Cellar/<formula>/<version>/lib
       puts "brew: Prepending to PYTHONPATH: #{py.site_packages}" if ARGV.verbose?
       mkdir_p py.site_packages
-      ENV.prepend 'PYTHONPATH', py.site_packages, ':'
+      ENV.prepend 'PYTHONPATH', py.site_packages, File::PATH_SEPARATOR
       ENV['PYTHON'] = py.binary
-      ENV.prepend 'CMAKE_INCLUDE_PATH', py.incdir, ':'
-      ENV.prepend 'PKG_CONFIG_PATH', py.pkg_config_path, ':' if py.pkg_config_path
-      ENV.prepend 'PATH', py.binary.dirname, ':' unless py.from_osx?
+      ENV.prepend 'CMAKE_INCLUDE_PATH', py.incdir, File::PATH_SEPARATOR
+      ENV.prepend 'PKG_CONFIG_PATH', py.pkg_config_path, File::PATH_SEPARATOR if py.pkg_config_path
+      ENV.prepend 'PATH', py.binary.dirname, File::PATH_SEPARATOR unless py.from_osx?
       #Note: Don't set LDFLAGS to point to the Python.framework, because
       #      it breaks builds (for example scipy.)
 
diff --git a/Library/Homebrew/requirements/python_dependency.rb b/Library/Homebrew/requirements/python_dependency.rb
index 5eca9cf302..6a18883df8 100644
--- a/Library/Homebrew/requirements/python_dependency.rb
+++ b/Library/Homebrew/requirements/python_dependency.rb
@@ -122,7 +122,7 @@ class PythonInstalled < Requirement
       else
         # Using the ORIGINAL_PATHS here because in superenv, the user
         # installed external Python is not visible otherwise.
-        which(@name, ORIGINAL_PATHS.join(':'))
+        which(@name, ORIGINAL_PATHS.join(File::PATH_SEPARATOR))
       end
     end
   end
@@ -252,12 +252,12 @@ class PythonInstalled < Requirement
     file.write(sitecustomize)
 
     # For non-system python's we add the opt_prefix/bin of python to the path.
-    ENV.prepend 'PATH', binary.dirname, ':' unless from_osx?
+    ENV.prepend 'PATH', binary.dirname, File::PATH_SEPARATOR unless from_osx?
 
     ENV['PYTHONHOME'] = nil  # to avoid fuck-ups.
     ENV['PYTHONPATH'] = if brewed? then nil; else global_site_packages.to_s; end
-    ENV.append 'CMAKE_INCLUDE_PATH', incdir, ':'
-    ENV.append 'PKG_CONFIG_PATH', pkg_config_path, ':' if pkg_config_path
+    ENV.append 'CMAKE_INCLUDE_PATH', incdir, File::PATH_SEPARATOR
+    ENV.append 'PKG_CONFIG_PATH', pkg_config_path, File::PATH_SEPARATOR if pkg_config_path
     # We don't set the -F#{framework} here, because if Python 2.x and 3.x are
     # used, `Python.framework` is ambiguous. However, in the `python do` block
     # we can set LDFLAGS+="-F#{framework}" because only one is temporarily set.
diff --git a/Library/Homebrew/test/testing_env.rb b/Library/Homebrew/test/testing_env.rb
index 5c2efed73a..9bc5d871fb 100644
--- a/Library/Homebrew/test/testing_env.rb
+++ b/Library/Homebrew/test/testing_env.rb
@@ -33,7 +33,7 @@ MACOS = true
 MACOS_FULL_VERSION = `/usr/bin/sw_vers -productVersion`.chomp
 MACOS_VERSION = ENV.fetch('MACOS_VERSION') { MACOS_FULL_VERSION[/10\.\d+/] }.to_f
 
-ORIGINAL_PATHS = ENV['PATH'].split(':').map{ |p| Pathname.new(p).expand_path rescue nil }.compact.freeze
+ORIGINAL_PATHS = ENV['PATH'].split(File::PATH_SEPARATOR).map{ |p| Pathname.new(p).expand_path rescue nil }.compact.freeze
 
 module Homebrew extend self
   include FileUtils
diff --git a/Library/Homebrew/utils.rb b/Library/Homebrew/utils.rb
index 2224e4ed00..b10764803a 100644
--- a/Library/Homebrew/utils.rb
+++ b/Library/Homebrew/utils.rb
@@ -167,7 +167,7 @@ def puts_columns items, star_items=[]
 end
 
 def which cmd, path=ENV['PATH']
-  dir = path.split(':').find {|p| File.executable? File.join(p, cmd)}
+  dir = path.split(File::PATH_SEPARATOR).find {|p| File.executable? File.join(p, cmd)}
   Pathname.new(File.join(dir, cmd)) unless dir.nil?
 end