diff --git a/metropolis/proto/private/BUILD.bazel b/metropolis/proto/private/BUILD.bazel
new file mode 100644
index 0000000..8f7cd50
--- /dev/null
+++ b/metropolis/proto/private/BUILD.bazel
@@ -0,0 +1,23 @@
+load("@rules_proto//proto:defs.bzl", "proto_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
+
+proto_library(
+    name = "private_proto",
+    srcs = ["private.proto"],
+    visibility = ["//metropolis:__subpackages__"],
+)
+
+go_proto_library(
+    name = "private_go_proto",
+    importpath = "source.monogon.dev/metropolis/proto/private",
+    proto = ":private_proto",
+    visibility = ["//metropolis:__subpackages__"],
+)
+
+go_library(
+    name = "go_default_library",
+    embed = [":private_go_proto"],
+    importpath = "source.monogon.dev/metropolis/proto/private",
+    visibility = ["//metropolis:__subpackages__"],
+)