diff --git a/build/static_binary_tarball/spec/BUILD.bazel b/build/static_binary_tarball/spec/BUILD.bazel
new file mode 100644
index 0000000..e79a202
--- /dev/null
+++ b/build/static_binary_tarball/spec/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 = "spec_proto",
+    srcs = ["spec.proto"],
+    visibility = ["//visibility:public"],
+)
+
+go_proto_library(
+    name = "spec_go_proto",
+    importpath = "source.monogon.dev/build/static_binary_tarball/spec",
+    proto = ":spec_proto",
+    visibility = ["//visibility:public"],
+)
+
+go_library(
+    name = "go_default_library",
+    embed = [":spec_go_proto"],
+    importpath = "source.monogon.dev/build/static_binary_tarball/spec",
+    visibility = ["//visibility:public"],
+)
diff --git a/build/static_binary_tarball/spec/spec.proto b/build/static_binary_tarball/spec/spec.proto
new file mode 100644
index 0000000..b47d137
--- /dev/null
+++ b/build/static_binary_tarball/spec/spec.proto
@@ -0,0 +1,32 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package spec;
+
+// Spec is a spec of what goes into a static_binary_tarball
+message Spec {
+  repeated File file = 1;
+}
+
+// File is a single file in the tarball
+message File {
+  // src contains the path of the file on the build host
+  string src = 1;
+  // path contains the path in the tarball
+  string path = 2;
+}
\ No newline at end of file