diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index fd44bcd8..4a888d3e 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -1,5 +1,9 @@
 name: check
-on: [push,pull_request]
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
 jobs:
   build:
     runs-on: ubuntu-latest