diff --git a/meshtastic/serial_interface.py b/meshtastic/serial_interface.py
index 7475ca2..758ee2c 100644
--- a/meshtastic/serial_interface.py
+++ b/meshtastic/serial_interface.py
@@ -56,14 +56,17 @@ class SerialInterface(StreamInterface):
 
     def connect(self) -> None:
         logger.debug(f"Connecting to {self.devPath}")
+        dev_path = self.devPath
+        if dev_path is None:
+            raise RuntimeError("Serial device path is not set")
 
         if sys.platform != "win32":
-            with open(self.devPath, encoding="utf8") as f:
+            with open(dev_path, encoding="utf8") as f:
                 self._set_hupcl_with_termios(f)
             time.sleep(0.1)
 
         self.stream = serial.Serial(
-            self.devPath, 115200, exclusive=True, timeout=0.5, write_timeout=0
+            dev_path, 115200, exclusive=True, timeout=0.5, write_timeout=0
         )
         self.stream.flush()	# type: ignore[attr-defined]
         time.sleep(0.1)
diff --git a/meshtastic/tests/test_main.py b/meshtastic/tests/test_main.py
index 048614e..b664665 100644
--- a/meshtastic/tests/test_main.py
+++ b/meshtastic/tests/test_main.py
@@ -7,6 +7,7 @@ import platform
 import re
 import sys
 import tempfile
+from types import SimpleNamespace
 from unittest.mock import mock_open, MagicMock, patch
 
 import pytest
@@ -1722,11 +1723,9 @@ def test_main_onReceive_with_sendtext(caplog, capsys):
 
 @pytest.mark.unit
 @pytest.mark.usefixtures("reset_mt_config")
-def test_main_onReceive_with_text(caplog, capsys):
-    """Test onReceive with text"""
-    args = MagicMock()
-    args.sendtext.return_value = "foo"
-    mt_config.args = args
+def test_main_onReceive_with_text_replies_on_target_channel(caplog, capsys):
+    """Test onReceive replies when channel matches --ch-index (default 0)."""
+    mt_config.args = SimpleNamespace(reply=True, ch_index=0, sendtext=None)
 
     # Note: 'TEXT_MESSAGE_APP' value is 1
     # Note: Some of this is faked below.
@@ -1752,6 +1751,83 @@ def test_main_onReceive_with_text(caplog, capsys):
         assert re.search(r"in onReceive", caplog.text, re.MULTILINE)
         out, err = capsys.readouterr()
         assert re.search(r"Sending reply", out, re.MULTILINE)
+        iface.sendText.assert_called_once_with(
+            "got msg 'faked' with rxSnr: 6.0 and hopLimit: 3", channelIndex=0
+        )
+        assert err == ""
+
+
+@pytest.mark.unit
+@pytest.mark.usefixtures("reset_mt_config")
+def test_main_onReceive_with_text_ignores_non_target_channel(caplog, capsys):
+    """Test onReceive does not reply when packet channel differs from --ch-index."""
+    mt_config.args = SimpleNamespace(reply=True, ch_index=1, sendtext=None)
+
+    packet = {
+        "to": 4294967295,
+        "decoded": {"portnum": 1, "payload": "hello", "text": "faked"},
+        "id": 334776977,
+        "hop_limit": 3,
+        "want_ack": True,
+        "rxSnr": 6.0,
+        "hopLimit": 3,
+        "raw": "faked",
+        "fromId": "!28b5465c",
+        "toId": "^all",
+        "channel": 0,
+    }
+
+    iface = MagicMock(autospec=SerialInterface)
+    iface.myInfo.my_node_num = 4294967295
+
+    with patch("meshtastic.serial_interface.SerialInterface", return_value=iface):
+        with caplog.at_level(logging.DEBUG):
+            onReceive(packet, iface)
+        assert re.search(r"in onReceive", caplog.text, re.MULTILINE)
+        out, err = capsys.readouterr()
+        assert re.search(
+            r"Ignored message on channel 0 \(waiting for channel 1\)", out, re.MULTILINE
+        )
+        iface.sendText.assert_not_called()
+        assert err == ""
+
+
+@pytest.mark.unit
+@pytest.mark.usefixtures("reset_mt_config")
+def test_main_onReceive_with_text_replies_on_explicit_matching_channel(caplog, capsys):
+    """Test onReceive replies when explicit packet channel matches --ch-index."""
+    mt_config.args = SimpleNamespace(reply=True, ch_index=2, sendtext=None)
+
+    packet = {
+        "to": 4294967295,
+        "decoded": {"portnum": 1, "payload": "hello", "text": "faked"},
+        "id": 334776977,
+        "hop_limit": 3,
+        "want_ack": True,
+        "rxSnr": 6.0,
+        "hopLimit": 3,
+        "raw": "faked",
+        "fromId": "!28b5465c",
+        "toId": "^all",
+        "channel": 2,
+    }
+
+    iface = MagicMock(autospec=SerialInterface)
+    iface.myInfo.my_node_num = 4294967295
+
+    with patch("meshtastic.serial_interface.SerialInterface", return_value=iface):
+        with caplog.at_level(logging.DEBUG):
+            onReceive(packet, iface)
+        assert re.search(r"in onReceive", caplog.text, re.MULTILINE)
+        out, err = capsys.readouterr()
+        assert re.search(
+            r"Received channel 2\. Sending reply: got msg 'faked' with rxSnr: 6.0 and hopLimit: 3",
+            out,
+            re.MULTILINE,
+        )
+        iface.sendText.assert_called_once_with(
+            "got msg 'faked' with rxSnr: 6.0 and hopLimit: 3", channelIndex=2
+        )
         assert err == ""