diff --git a/lib/next_ls/lsp_supervisor.ex b/lib/next_ls/lsp_supervisor.ex
index 59bd7e66..d9788164 100644
--- a/lib/next_ls/lsp_supervisor.ex
+++ b/lib/next_ls/lsp_supervisor.ex
@@ -29,7 +29,7 @@ defmodule NextLS.LSPSupervisor do
             [communication: {GenLSP.Communication.TCP, [port: opts[:port]]}]
 
           true ->
-            raise "Unknown option"
+            raise "Unknown option. Expected --stdio or --port=INTEGER."
         end
 
       children = [