diff --git a/tools/idf_py_actions/serial_ext.py b/tools/idf_py_actions/serial_ext.py
index 4deb379a7f..6dbff88b5b 100644
--- a/tools/idf_py_actions/serial_ext.py
+++ b/tools/idf_py_actions/serial_ext.py
@@ -27,7 +27,7 @@ def action_extensions(base_actions, project_path):
                   ports[0].encode("ascii", "ignore"))
             return ports[0]
         except IndexError:
-            raise RuntimeError(
+            raise FatalError(
                 "No serial ports found. Connect a device, or use '-p PORT' option to set a specific port.")
 
     def _get_esptool_args(args):
diff --git a/tools/idf_py_actions/tools.py b/tools/idf_py_actions/tools.py
index 788bcca5e3..b7a7998c0a 100644
--- a/tools/idf_py_actions/tools.py
+++ b/tools/idf_py_actions/tools.py
@@ -71,6 +71,7 @@ def run_tool(tool_name, args, cwd, env=dict()):
             return "'" + arg + "'"
         return arg
 
+    args = [str(arg) for arg in args]
     display_args = " ".join(quote_arg(arg) for arg in args)
     print("Running %s in directory %s" % (tool_name, quote_arg(cwd)))
     print('Executing "%s"...' % str(display_args))