diff --git a/Rakefile b/Rakefile
index 8c33355..60806d9 100644
--- a/Rakefile
+++ b/Rakefile
@@ -9,8 +9,9 @@ RSpec::Core::RakeTask.new(:spec)
 namespace :spec do
   desc "Run on three Rubies"
   task :platforms do
-    system %{rvm 1.8.7,1.9.2,ree ruby bundle}
-    system %{rvm 1.8.7,1.9.2,ree ruby bundle exec rake spec}
+    prefix = "rvm 1.8.7,1.9.2,ree ruby"
+    system %{#{prefix} bundle}
+    system %{#{prefix} bundle exec rake spec}
     exit $?.exitstatus
   end
 end