diff --git a/.github/workflows/update-dependencies.yml b/.github/workflows/update-dependencies.yml
index 208b36c4..c2fcada5 100644
--- a/.github/workflows/update-dependencies.yml
+++ b/.github/workflows/update-dependencies.yml
@@ -1,6 +1,15 @@
 name: Update dependencies
 
 on:
+  pull_request:
+    paths:
+      - '.github/workflows/update-dependencies.yml'
+      - 'bin/update_pythons.py'
+      - 'bin/update_docker.py'
+      - 'bin/update_virtualenv.py'
+      - 'bin/projects.py'
+      - 'docs/data/projects.yml'
+      - 'noxfile.py'
   workflow_dispatch:
   schedule:
     - cron: '0 6 * * 1'  # "At 06:00 on Monday."