diff --git a/.github/workflows/build-notebooks-TEMPLATE.yaml b/.github/workflows/build-notebooks-TEMPLATE.yaml
index e826d79b5..2c9990ec8 100644
--- a/.github/workflows/build-notebooks-TEMPLATE.yaml
+++ b/.github/workflows/build-notebooks-TEMPLATE.yaml
@@ -74,13 +74,14 @@ jobs:
           IMAGE_REGISTRY: "ghcr.io/${{ github.repository }}/workbench-images"
           CONTAINER_BUILD_CACHE_ARGS: "--cache-from ${{ env.CACHE }} --cache-to ${{ env.CACHE }}"
 
+      # https://ttl.sh/, Anonymous & ephemeral Docker image registry
       # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request
       - name: "pull_request: make ${{ inputs.target }}"
         run: "make ${{ inputs.target }}"
         if: "${{ fromJson(inputs.github).event_name == 'pull_request' }}"
         env:
           IMAGE_TAG: "${{ github.head_ref }}_${{ github.sha }}"
-          IMAGE_REGISTRY: "ghcr.io/${{ github.repository }}/workbench-images/pr${{ fromJson(inputs.github).event.number }}"
+          IMAGE_REGISTRY: "ttl.sh/${{ github.repository }}/workbench-images/pr${{ fromJson(inputs.github).event.number }}"
           CONTAINER_BUILD_CACHE_ARGS: "--cache-from ${{ env.CACHE }}"
 
       - run: df -h