diff --git a/src/ruby/lib/grpc/generic/service.rb b/src/ruby/lib/grpc/generic/service.rb
index 7cb9f1cc99d..06ea5b3f179 100644
--- a/src/ruby/lib/grpc/generic/service.rb
+++ b/src/ruby/lib/grpc/generic/service.rb
@@ -110,7 +110,7 @@ module GRPC
         rpc_descs[name] = RpcDesc.new(name, input, output,
                                       marshal_class_method,
                                       unmarshal_class_method)
-        define_method(name) do
+        define_method(GenericService.underscore(name.to_s).to_sym) do
           fail GRPC::BadStatus, GRPC::Core::StatusCodes::UNIMPLEMENTED
         end
       end