diff --git a/Library/Homebrew/cmd/cleanup.rb b/Library/Homebrew/cmd/cleanup.rb
index ba9745f1aa..3f6471af98 100644
--- a/Library/Homebrew/cmd/cleanup.rb
+++ b/Library/Homebrew/cmd/cleanup.rb
@@ -51,10 +51,11 @@ module Homebrew extend self
   def clean_cache
     HOMEBREW_CACHE.children.each do |pn|
       next unless pn.file?
-      pn.stem =~ /^(.+)-(.+)$/ # greedy so works even if formula-name has hyphens in it
-      if $1 and $2
-        f = Formula.factory($1) rescue nil
-        if not f or (f.version != $2 or ARGV.switch? "s" and not f.installed?)
+      version = pn.version
+      name = pn.basename.to_s.match(/(.*)-(#{version})/).captures.first rescue nil
+      if name and version
+        f = Formula.factory(name) rescue nil
+        if not f or (f.version != version or ARGV.switch? "s" and not f.installed?)
           puts "Removing #{pn}..."
           rm pn unless ARGV.switch? 'n'
         end