diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 587c967..38d6597 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -2,7 +2,8 @@ name: build
 
 on:
   pull_request:
-    types: opened
+    branches: [master]
+    types: [opened]
   push:
     branches:
       - master