diff --git a/metropolis/proto/ext/gomod-generated-placeholder.go b/metropolis/proto/ext/gomod-generated-placeholder.go
new file mode 100644
index 0000000..b39f0bb
--- /dev/null
+++ b/metropolis/proto/ext/gomod-generated-placeholder.go
@@ -0,0 +1 @@
+package ext