diff --git a/Library/Homebrew/cmd/doctor.rb b/Library/Homebrew/cmd/doctor.rb
index 374b66c2e1..2c0d1bf4a1 100644
--- a/Library/Homebrew/cmd/doctor.rb
+++ b/Library/Homebrew/cmd/doctor.rb
@@ -104,7 +104,7 @@ def check_for_macgpg2
 end
 
 def __check_stray_files(dir, pattern, white_list, message)
-  return unless Dir.exist?(dir)
+  return unless File.directory?(dir)
 
   files = Dir.chdir(dir) {
     Dir[pattern].select { |f| File.file?(f) && !File.symlink?(f) }