diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 77e7616..4af5d46 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -3,9 +3,7 @@ name: Build container images for OVAL
 
 on:
   push:
-    branches: [ $default-branch ]
-  pull_request:
-    branches: [ $default-branch ]
+    branches: ['main']
 
 jobs:
   buildx:
@@ -38,7 +36,7 @@ jobs:
         uses: docker/build-push-action@v2
         with:
           builder: ${{ steps.buildx.outputs.name }}
-          platforms: linux/amd64,linux/arm64,linux/s390x,linux/ppc64le
+          platforms: linux/amd64,linux/arm64
           context: .
           file: Containerfile
           push: ${{ github.event_name != 'pull_request' }}