diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e1d464e..5eaf37a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,6 +1,10 @@
 name: Build and test
 
-on: [push, pull_request]
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '0 0 * * *'  # run nightly at midnight
 
 jobs:
   tests: