diff --git a/Library/Homebrew/cmd/tap.rb b/Library/Homebrew/cmd/tap.rb
index c2dbd0f9da..58132faca6 100644
--- a/Library/Homebrew/cmd/tap.rb
+++ b/Library/Homebrew/cmd/tap.rb
@@ -110,7 +110,7 @@ module Homebrew extend self
 
   def tap_args
     ARGV.first =~ %r{^(\S+)/(homebrew-)?(\w+)$}
-    raise "Invalid usage" unless $1 and $3
+    raise "Invalid tap name" unless $1 && $3
     [$1, $3]
   end