diff --git a/Library/Homebrew/cmd/doctor.rb b/Library/Homebrew/cmd/doctor.rb
index d7f8538512..820dd88973 100644
--- a/Library/Homebrew/cmd/doctor.rb
+++ b/Library/Homebrew/cmd/doctor.rb
@@ -1181,6 +1181,25 @@ end
     EOS
   end
 
+  def check_for_external_cmd_name_conflict
+    cmds = paths.map { |p| Dir["#{p}/brew-*"] }.flatten.uniq
+    cmds = cmds.select { |cmd| File.file?(cmd) && File.executable?(cmd) }
+    cmd_map = {}
+    cmds.each do |cmd|
+      cmd_name = File.basename(cmd, ".rb")
+      cmd_map[cmd_name] ||= []
+      cmd_map[cmd_name] << cmd
+    end
+    cmd_map.reject! { |cmd_name, cmd_paths| cmd_paths.size == 1 }
+    return if cmd_map.empty?
+    s = "You have external commands with conflicting names."
+    cmd_map.each do |cmd_name, cmd_paths|
+      s += "\n\nFound command `#{cmd_name}` in following places:\n"
+      s += cmd_paths.map { |f| "  #{f}" }.join("\n")
+    end
+    s
+  end
+
   def all
     methods.map(&:to_s).grep(/^check_/)
   end