diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 197b78b..08eb60d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -6,6 +6,12 @@ on:
     branches:
       - main
 
+# A newer push to the same ref supersedes this run: checks are
+# side-effect free, so cancelling the stale one costs nothing.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 env:
   FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true