diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index 6b2418d5d..9571825ca 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -1,6 +1,13 @@
 name: CI
 
-on: [ push, pull_request ]
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+on:
+  pull_request:
+    branches: [ master ]
+  workflow_dispatch:
 
 jobs:
   test: