diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 64fcafc..dcc0678 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -45,7 +45,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ['7.4', '8.0', '8.1', '8.2', '8.3', '8.4', '8.5']
+        # PRs test only the oldest and newest supported versions.
+        # Pushes to trunk/copilot branches test the full range.
+        php: ${{ github.event_name == 'push' && fromJSON('["7.4","8.0","8.1","8.2","8.3","8.4","8.5"]') || fromJSON('["7.4","8.5"]') }}
     steps:
       - uses: actions/checkout@v4