diff --git a/lib/mix/tasks/esp32_flash.ex b/lib/mix/tasks/esp32_flash.ex
index b432b95..efc2749 100644
--- a/lib/mix/tasks/esp32_flash.ex
+++ b/lib/mix/tasks/esp32_flash.ex
@@ -39,8 +39,6 @@ defmodule Mix.Tasks.Atomvm.Esp32.Flash do
     tool_args = [
       "--chip",
       chip,
-      "--port",
-      port,
       "--baud",
       baud,
       "--before",
@@ -59,6 +57,8 @@ defmodule Mix.Tasks.Atomvm.Esp32.Flash do
       "#{Project.config()[:app]}.avm"
     ]
 
+    tool_args = if port == "auto", do: tool_args, else: ["--port", port] ++ tool_args
+
     tool_full_path = get_esptool_path(idf_path)
     System.cmd(tool_full_path, tool_args, stderr_to_stdout: true, into: IO.stream(:stdio, 1))
   end