diff --git a/Library/Homebrew/cmd/install.rb b/Library/Homebrew/cmd/install.rb
index b77121a194..a8bd6454f3 100644
--- a/Library/Homebrew/cmd/install.rb
+++ b/Library/Homebrew/cmd/install.rb
@@ -18,7 +18,10 @@ module Homebrew extend self
       end
       if not File.exist? name and name =~ HOMEBREW_TAP_REGEX then
         require 'cmd/tap'
-        install_tap $1, $2
+        begin
+          install_tap $1, $2
+        rescue AlreadyTappedError => e
+        end
       end
     end unless ARGV.force?