diff --git a/Library/Homebrew/cmd/--prefix.rb b/Library/Homebrew/cmd/--prefix.rb
index f6e7d2ee29..956ab0403c 100644
--- a/Library/Homebrew/cmd/--prefix.rb
+++ b/Library/Homebrew/cmd/--prefix.rb
@@ -11,7 +11,9 @@ module Homebrew
     if ARGV.named.empty?
       puts HOMEBREW_PREFIX
     else
-      puts ARGV.resolved_formulae.map(&:installed_prefix)
+      puts ARGV.resolved_formulae.map { |f|
+        f.opt_prefix.exist? ? f.opt_prefix : f.installed_prefix
+      }
     end
   end
 end