diff --git a/.github/workflows/build-pack.yml b/.github/workflows/build-pack.yml
index ea23206..0789f4c 100644
--- a/.github/workflows/build-pack.yml
+++ b/.github/workflows/build-pack.yml
@@ -120,6 +120,10 @@ jobs:
           - 5432:5432
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
     steps:
+      - name: Check tile URLs work
+        run: |
+          curl -v -f -o "/tmp/test.tif" "https://s3.amazonaws.com/elevation-tiles-prod/geotiff/12/646/1537.tif"
+
       - uses: actions/checkout@v4
 
       - name: Install Ubuntu dependencies