diff --git a/src/proto/grpc/reflection/v1alpha/reflection.proto b/src/proto/grpc/reflection/v1alpha/reflection.proto
index 32cea75..276ff0e 100644
--- a/src/proto/grpc/reflection/v1alpha/reflection.proto
+++ b/src/proto/grpc/reflection/v1alpha/reflection.proto
@@ -94,6 +94,8 @@
     // file_containing_extension requests with transitive dependencies. As
     // the repeated label is not allowed in oneof fields, we use a
     // FileDescriptorResponse message to encapsulate the repeated fields.
+    // The reflection service is allowed to avoid sending FileDescriptorProtos
+    // that were previously sent in response to earlier requests in the stream.
     FileDescriptorResponse file_descriptor_response = 4;
 
     // This message is used to answer all_extension_numbers_of_type requst.