diff --git a/.github/workflows/deploy_heroku.yml b/.github/workflows/deploy_heroku.yml
index 3a4918e..ec16518 100644
--- a/.github/workflows/deploy_heroku.yml
+++ b/.github/workflows/deploy_heroku.yml
@@ -1,5 +1,6 @@
 on:
   push:
+    branch: master
 jobs:
   deploy:
     concurrency: http4k-irc