diff --git a/Library/Homebrew/cmd/doctor.rb b/Library/Homebrew/cmd/doctor.rb
index 2134de3d3d..6f7b3a98b2 100644
--- a/Library/Homebrew/cmd/doctor.rb
+++ b/Library/Homebrew/cmd/doctor.rb
@@ -187,9 +187,9 @@ def check_for_other_package_managers
 end
 
 def check_for_broken_symlinks
+  require 'keg'
   broken_symlinks = []
-  %w[lib include sbin bin etc share].each do |d|
-    d = HOMEBREW_PREFIX/d
+  Keg::PRUNEABLE_DIRECTORIES.map { |d| HOMEBREW_PREFIX/d }.each do |d|
     next unless d.directory?
     d.find do |pn|
       broken_symlinks << pn if pn.symlink? and pn.readlink.expand_path.to_s =~ /^#{HOMEBREW_PREFIX}/ and not pn.exist?
diff --git a/Library/Homebrew/cmd/prune.rb b/Library/Homebrew/cmd/prune.rb
index 75e6026df8..394b8ad7ff 100644
--- a/Library/Homebrew/cmd/prune.rb
+++ b/Library/Homebrew/cmd/prune.rb
@@ -9,7 +9,7 @@ module Homebrew extend self
     $d = 0
     dirs = []
 
-    %w[bin sbin etc lib include share Library/LinkedKegs].map{ |d| HOMEBREW_PREFIX+d }.each do |path|
+    Keg::PRUNEABLE_DIRECTORIES.map{ |d| HOMEBREW_PREFIX/d }.each do |path|
       next unless path.directory?
       path.find do |path|
         path.extend ObserverPathnameExtension
diff --git a/Library/Homebrew/keg.rb b/Library/Homebrew/keg.rb
index ba394266c9..8bd779ecac 100644
--- a/Library/Homebrew/keg.rb
+++ b/Library/Homebrew/keg.rb
@@ -10,6 +10,8 @@ class Keg < Pathname
   # locale-specific directories have the form language[_territory][.codeset][@modifier]
   LOCALEDIR_RX = /(locale|man)\/([a-z]{2}|C|POSIX)(_[A-Z]{2})?(\.[a-zA-Z\-0-9]+(@.+)?)?/
   INFOFILE_RX = %r[info/([^.].*?\.info|dir)$]
+  TOP_LEVEL_DIRECTORIES = %w[bin etc include lib sbin share var]
+  PRUNEABLE_DIRECTORIES = %w[bin etc include lib sbin share Library/LinkedKegs]
 
   # if path is a file in a keg then this will return the containing Keg object
   def self.for path
@@ -31,7 +33,7 @@ class Keg < Pathname
     # of files and directories linked
     $n=$d=0
 
-    %w[bin etc lib include sbin share var].map{ |d| self/d }.each do |src|
+    TOP_LEVEL_DIRECTORIES.map{ |d| self/d }.each do |src|
       next unless src.exist?
       src.find do |src|
         next if src == self