diff --git a/.travis.yml b/.travis.yml
index 35dbe4f181..c3c05030e0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@ sudo: false
 dist: trusty
 node_js: '9'
 addons:
-  firefox: latest
+  firefox: "66.0"
   chrome: stable
 cache:
   directories: