diff --git a/.github/workflows/treehash.yml b/.github/workflows/treehash.yml
index 37c2cd88d..d25901abe 100644
--- a/.github/workflows/treehash.yml
+++ b/.github/workflows/treehash.yml
@@ -6,6 +6,7 @@ on:
       - 'master'
       - 'release-'
     tags: '*'
+  pull_request:
 
 concurrency:
   # group by workflow and ref; the last slightly strange component ensures that for pull