diff --git a/.github/workflows/periodic-build-from-head.yml b/.github/workflows/periodic-build-from-head.yml
index 92f7d79..95b8b7f 100644
--- a/.github/workflows/periodic-build-from-head.yml
+++ b/.github/workflows/periodic-build-from-head.yml
@@ -1,5 +1,6 @@
 name: brew install --HEAD
 on:
+  pull_request:
   schedule:
     - cron:  '0 3 * * *'
 concurrency: