diff --git a/.travis.yml b/.travis.yml
index f147e3ea95..f4a8d5e8e5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,7 +20,7 @@ before_script:
   update-types".' && false)
 script:
 - wct -l chrome
-- wct -l firefox
+- xvfb-run wct -l firefox
 - if [ "${TRAVIS_PULL_REQUEST}" = "false" ]; then travis_wait 30 ./util/travis-sauce-test.sh; fi
 env:
   global:
diff --git a/package.json b/package.json
index ed5ee6699b..9474674ba0 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,7 @@
     "polymer-build": "^2.1.1",
     "run-sequence": "^2.2.0",
     "through2": "^2.0.0",
-    "web-component-tester": "^6.5.0"
+    "web-component-tester": "^6.9.0"
   },
   "scripts": {
     "build": "gulp",
diff --git a/test/unit/globals.html b/test/unit/globals.html
index 45b1f1eb5c..73cbee94f7 100644
--- a/test/unit/globals.html
+++ b/test/unit/globals.html
@@ -85,7 +85,10 @@
     // weird safari + selenium globals
     alert: true,
     confirm: true,
-    prompt: true
+    prompt: true,
+
+    // weird FF globals
+    XULElement: true
   };
 
   test('check global leakage', function() {
diff --git a/util/travis-sauce-test.sh b/util/travis-sauce-test.sh
index 7d760f075b..ffd1487a3d 100755
--- a/util/travis-sauce-test.sh
+++ b/util/travis-sauce-test.sh
@@ -9,4 +9,4 @@
 # subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 #
 set -x
-wct -s 'windows 10/microsoftedge@14' -s 'windows 10/microsoftedge@15' -s 'windows 10/microsoftedge@16' -s 'windows 8.1/internet explorer@11' -s 'os x 10.11/safari@9' -s 'macos 10.12/safari@10' -s 'macos 10.13/safari@11' -s 'Linux/chrome@41'
\ No newline at end of file
+wct -s 'windows 10/microsoftedge@15' -s 'windows 10/microsoftedge@17' -s 'windows 8.1/internet explorer@11' -s 'os x 10.11/safari@9' -s 'macos 10.13/safari@11' -s 'macos 10.13/safari@12' -s 'Linux/chrome@41' -s 'windows/firefox@62'
\ No newline at end of file
diff --git a/wct.conf.json b/wct.conf.json
index 5b315d7362..8c061cea55 100644
--- a/wct.conf.json
+++ b/wct.conf.json
@@ -10,9 +10,6 @@
           "headless",
           "disable-gpu",
           "no-sandbox"
-        ],
-        "firefox": [
-          "-headless"
         ]
       }
     }