diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index dd402da..31a2e8d 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -2,7 +2,10 @@
 #
 # SPDX-License-Identifier: MPL-2.0
 name: Nix flake check
-on: push
+on:
+  pull_request:
+  push:
+      branches: master
 
 jobs:
   validate: