diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index b85adc95..283848c5 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -93,6 +93,13 @@ jobs:
       DOCKER_OSES: "${{ matrix.DOCKER_OSES }}"
       DOCKER_LANGUAGES: "${{ matrix.DOCKER_LANGUAGES }}"
     steps:
+      - name: "DEBUG: Disk space usage"
+        run: >-
+          docker system df &&
+          docker image ls -a --format
+          '{{.CreatedAt}} {{.Repository}}:{{.Tag}} {{.CreatedSince}} {{.Size}}'
+          | sort | head -n 1000
+
       # Shared or common set up:
       - name: "Checkout source from VCS"
         uses: "actions/checkout@master"