diff --git a/.github/workflows/diff_headers.yml b/.github/workflows/diff_headers.yml
index b8637a9..6c033a1 100644
--- a/.github/workflows/diff_headers.yml
+++ b/.github/workflows/diff_headers.yml
@@ -1,6 +1,7 @@
 name: Diff headers
 
 on:
+  pull_request:
   workflow_dispatch:
     inputs:
       base-version: