diff --git a/.github/workflows/slow-tests.yml b/.github/workflows/slow-tests.yml
index 3dd5393e..1cf63ab9 100644
--- a/.github/workflows/slow-tests.yml
+++ b/.github/workflows/slow-tests.yml
@@ -1,6 +1,7 @@
 name: Slow tests
 
 on:
+  pull_request:
   schedule:
     # Every weekday at 03:49 UTC, see https://crontab.guru/
     - cron: "49 3 * * 1-5"