diff --git a/.gitea/workflows/images.yml b/.gitea/workflows/images.yml
index 56dc408d..21db4a8d 100644
--- a/.gitea/workflows/images.yml
+++ b/.gitea/workflows/images.yml
@@ -54,3 +54,14 @@ jobs:
               .
             echo "pushed $image"
           done
+
+      # The images live in the registry now; the runner keeps only a bounded build cache. Without this the
+      # runner's 10Gi Docker volume fills up after a handful of builds (no space left on device mid-build).
+      - name: Free the runner's disk
+        if: always()
+        run: |
+          set -u
+          docker image ls --format '{{.Repository}}:{{.Tag}}' | grep "^$IMAGE_PREFIX/" | xargs -r docker image rm -f
+          docker image prune -f
+          docker builder prune -f --keep-storage 4GB
+          docker system df