diff --git a/.travis.yml b/.travis.yml
index 360d0ab..0a0324b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,7 @@ sudo: false
 env:
   matrix:
   - BROWSER=chromium EXT=zip
+  - BROWSER=firefox EXT=xpi
 script: ./tools/make-${BROWSER}.sh all
 deploy:
   provider: releases