diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a1931bda..772b6611 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,12 +1,12 @@
 name: Build
 on:
-  - push
-  - pull_request
+  pull_request:
+  push:
+    branches: [ main ]
 
 jobs:
   build:
     name: Ruby ${{ matrix.ruby }} / Rails ${{ matrix.rails }}
-    if: github.event_name == 'push' || github.event.pull_request.head.repo.full_name != github.repository
     strategy:
       fail-fast: false
       matrix: