diff --git a/envoy/config/core/v3/config_source.proto b/envoy/config/core/v3/config_source.proto
index c1293013..3277fdf2 100644
--- a/envoy/config/core/v3/config_source.proto
+++ b/envoy/config/core/v3/config_source.proto
@@ -281,3 +281,7 @@ message ExtensionConfigSource {
   // if they do not match any type URL in the set.
   repeated string type_urls = 4 [(validate.rules).repeated = {min_items: 1}];
 }
+
+// A placeholder proto for the registration for the REST subscription implementation.
+message RestSubscription {
+}