diff --git a/services/reconciler/Dockerfile b/services/reconciler/Dockerfile
index d98da07..d7899a3 100644
--- a/services/reconciler/Dockerfile
+++ b/services/reconciler/Dockerfile
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.10
+# syntax=mirror.gcr.io/docker/dockerfile:1.10@sha256:865e5dd094beca432e8c0a1d5e1c465db5f998dca4e439981029b3b81fb39ed5
 #
 # svcforge reconciler. Build from the REPO ROOT:
 #     docker buildx build -f services/reconciler/Dockerfile -t svcforge/reconciler:dev .
diff --git a/services/worker/Dockerfile b/services/worker/Dockerfile
index 6764941..b4a688e 100644
--- a/services/worker/Dockerfile
+++ b/services/worker/Dockerfile
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.10
+# syntax=mirror.gcr.io/docker/dockerfile:1.10@sha256:865e5dd094beca432e8c0a1d5e1c465db5f998dca4e439981029b3b81fb39ed5
 #
 # svcforge worker. Build from the REPO ROOT:
 #     docker buildx build -f services/worker/Dockerfile -t svcforge/worker:dev .