diff --git a/.github/workflows/run_all_tests.yml b/.github/workflows/run_all_tests.yml
index b43780f..e981cf2 100644
--- a/.github/workflows/run_all_tests.yml
+++ b/.github/workflows/run_all_tests.yml
@@ -2,6 +2,8 @@ name: Run all tests
 on:
   pull_request:
     types: [synchronize, opened, reopened]
+    branches:
+      - main
   schedule:
     - cron: '0 5 * * 0'  # once every Sunday at midnight ET
   workflow_dispatch: