diff --git a/Library/Homebrew/cmd/cleanup.rb b/Library/Homebrew/cmd/cleanup.rb
index 5cf7ef00ee..df66a85d6a 100644
--- a/Library/Homebrew/cmd/cleanup.rb
+++ b/Library/Homebrew/cmd/cleanup.rb
@@ -84,6 +84,7 @@ module Homebrew extend self
   end
 
   def cleanup_lockfiles
+    return unless HOMEBREW_CACHE_FORMULA.directory?
     candidates = HOMEBREW_CACHE_FORMULA.children
     lockfiles  = candidates.select { |f| f.file? && f.extname == '.brewing' }
     lockfiles.select(&:readable?).each do |file|