diff --git a/metropolis/test/localregistry/spec/manifest.proto b/metropolis/test/localregistry/spec/manifest.proto
new file mode 100644
index 0000000..bb53581
--- /dev/null
+++ b/metropolis/test/localregistry/spec/manifest.proto
@@ -0,0 +1,19 @@
+syntax = "proto3";
+
+package monogon.metropolis.pkg.localregistry;
+
+option go_package = "source.monogon.dev/metropolis/test/localregistry/spec";
+
+// Single image metadata
+message Image {
+    // Name of the image (no domain or tag, just slash-separated path)
+    string name = 1;
+    // Path to the image
+    string path = 2;
+}
+
+// Main message
+message Manifest {
+    // List of images for the local registry
+    repeated Image images = 1;
+}
\ No newline at end of file