diff --git a/.github/workflows/container_image.yml b/.github/workflows/container_image.yml
index f3079905..0f46ab68 100644
--- a/.github/workflows/container_image.yml
+++ b/.github/workflows/container_image.yml
@@ -1,6 +1,10 @@
 name: Build Docker image
 
-on: [push]
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
 
 jobs:
   docker: