diff --git a/Library/Homebrew/cmd/bottle.rb b/Library/Homebrew/cmd/bottle.rb
index e582620bbd17b1c0174f074b6ea51ea08ca59867..7b5df314e67739e28404fa681c5602b4c383a0cd 100644
--- a/Library/Homebrew/cmd/bottle.rb
+++ b/Library/Homebrew/cmd/bottle.rb
@@ -177,7 +177,9 @@ module Homebrew
       end
     end
 
-    root_url = ARGV.value("root_url")
+    root_url = ARGV.value("root-url")
+    # Use underscored version for legacy reasons. Remove at some point.
+    root_url ||= ARGV.value("root_url")
 
     bottle = BottleSpecification.new
     bottle.root_url(root_url) if root_url