diff --git a/.travis.yml b/.travis.yml
index 8f2dc190b244aaca066841f124e9091499d90d04..71c72ccf53d17f2e9ad8888d670925bb633f12f8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,10 @@ language: node_js
 email:
   on_failure: change
   on_success: never
+before_script:
+  - "export DISPLAY=:99.0"
+  - "sh -e /etc/init.d/xvfb start"
+  - sleep 3 # give xvfb some time to start
 after_success:
 - npm run coveralls
 env:
diff --git a/karma.conf.js b/karma.conf.js
index ac0286f7415ae16a4471dfe42f9188d8c5a50e38..2275e471dedd5f9b596fa37a2b318b62cf7e33d0 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -16,10 +16,7 @@ module.exports = function(config) {
   var customLaunchers = {};
   var browsers = [];
 
-  if (!process.env.SAUCE_USERNAME || !process.env.SAUCE_ACCESS_KEY) {
-    console.log('Running locally since SAUCE_USERNAME and SAUCE_ACCESS_KEY environment variables are set.');
-    browsers = ['Firefox', 'Chrome', 'Safari', 'Opera'];
-  } else {
+  if (process.env.SAUCE_USERNAME || process.env.SAUCE_ACCESS_KEY) {
     customLaunchers = {};
 
     var runAll = true;
@@ -99,6 +96,15 @@ module.exports = function(config) {
     }
 
     browsers = Object.keys(customLaunchers);
+  } else if (process.env.TRAVIS_PULL_REQUEST && process.env.TRAVIS_PULL_REQUEST !== 'false') {
+    console.log(
+      'Cannot run on Sauce Labs as encrypted environment variables are not available to PRs. ' +
+      'Running on Travis.'
+    );
+    browsers = ['Firefox'];
+  } else {
+    console.log('Running locally since SAUCE_USERNAME and SAUCE_ACCESS_KEY environment variables are not set.');
+    browsers = ['Firefox', 'Chrome', 'Safari', 'Opera'];
   }
 
   config.set({
@@ -199,7 +205,7 @@ module.exports = function(config) {
       }
     },
 
-    
+
     // Coverage reporting
     coverageReporter: {
       type: 'lcov',