diff --git a/.github/workflows/ci-testing.yml b/.github/workflows/ci-testing.yml
index 4a211150..2cd85c1a 100644
--- a/.github/workflows/ci-testing.yml
+++ b/.github/workflows/ci-testing.yml
@@ -1,6 +1,15 @@
 name: CI testing
 
-on: [push, pull_request]
+# https://help.github.com/en/actions/reference/events-that-trigger-workflows
+on:
+  # Trigger the workflow on push or pull request,
+  # but only for the master branch
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
 
 jobs:
   build: