diff --git a/.github/workflows/sphinx.yml b/.github/workflows/sphinx.yml
index 7a88c9d..ca70418 100644
--- a/.github/workflows/sphinx.yml
+++ b/.github/workflows/sphinx.yml
@@ -2,7 +2,7 @@
 name: Build Sphinx docu.
 
 on:
-  [push]
+  [pull_request]
 permissions:
   contents: write
 jobs: