diff --git a/Library/Homebrew/cmd/--prefix.rb b/Library/Homebrew/cmd/--prefix.rb
index 9a15203a9b..51d341d3ad 100644
--- a/Library/Homebrew/cmd/--prefix.rb
+++ b/Library/Homebrew/cmd/--prefix.rb
@@ -3,7 +3,7 @@ module Homebrew extend self
     if ARGV.named.empty?
       puts HOMEBREW_PREFIX
     else
-      puts ARGV.formulae.map{ |f| f.prefix }
+      puts ARGV.formulae.map{ |f| f.installed_prefix }
     end
   end
 end