diff --git a/spec/javascripts/support/jasmine_selenium_runner.yml b/spec/javascripts/support/jasmine_selenium_runner.yml
index 1417966f..8ae24edc 100644
--- a/spec/javascripts/support/jasmine_selenium_runner.yml
+++ b/spec/javascripts/support/jasmine_selenium_runner.yml
@@ -9,7 +9,7 @@ sauce:
   tags:
     - <%= ENV['TRAVIS_RUBY_VERSION'] || RUBY_VERSION %>
     - CI
-  tunnel_identifier: <%= ENV['TRAVIS_JOB_NUMBER'] %>
+  tunnel_identifier: <%= ENV['TRAVIS_JOB_NUMBER'] ? ENV["TRAVIS_JOB_NUMBER"].to_s : nil %>
   os: <%= ENV['SAUCE_OS'] %>
   browser_version: <%= ENV['SAUCE_BROWSER_VERSION'] %>