diff --git a/pcapkit/protocols/internet/mh.py b/pcapkit/protocols/internet/mh.py
index f5086ab4f6..a7a230d5ad 100644
--- a/pcapkit/protocols/internet/mh.py
+++ b/pcapkit/protocols/internet/mh.py
@@ -8050,7 +8050,7 @@ def _make_opt_mnp(self, type: 'Enum_Option', option: 'Optional[Data_MobileNetwor
 
         prefix_val = ipaddress.ip_network(prefix)
         if prefix_val.version != 6:
-            raise ProtocolError(f'{self.alias}: [OptNo {type}] invalid movile network prefix: {prefix!r}')
+            raise ProtocolError(f'{self.alias}: [OptNo {type}] invalid mobile network prefix: {prefix!r}')
         prefix_length = prefix_val.prefixlen
         prefix_addr = prefix_val.network_address
 
diff --git a/pcapkit/protocols/schema/internet/ipv4.py b/pcapkit/protocols/schema/internet/ipv4.py
index aa08caff97..0f156b9911 100644
--- a/pcapkit/protocols/schema/internet/ipv4.py
+++ b/pcapkit/protocols/schema/internet/ipv4.py
@@ -454,7 +454,7 @@ def post_process(self, packet: 'dict[str, Any]') -> 'Schema':
                     ts_val = datetime.timedelta(milliseconds=ts)
                 timestamp.add(ip_val, ts_val)
         else:
-            warn(f'IPv4: [OptNo {self.type}] invalid format: unknown timestmap flag: {ts_flag}', ProtocolWarning)
+            warn(f'IPv4: [OptNo {self.type}] invalid format: unknown timestamp flag: {ts_flag}', ProtocolWarning)
             self.data = self.ts_data[:used]
             timestamp = tuple(self.data)
 
diff --git a/tests/protocols/internet/test_message_spelling_2171_unit.py b/tests/protocols/internet/test_message_spelling_2171_unit.py
new file mode 100644
index 0000000000..35aba5ea06
--- /dev/null
+++ b/tests/protocols/internet/test_message_spelling_2171_unit.py
@@ -0,0 +1,53 @@
+# -*- coding: utf-8 -*-
+"""Two user-facing messages are spelt correctly.
+
+GitHub issue #2171: :meth:`TSOption.post_process
+<pcapkit.protocols.schema.internet.ipv4.TSOption.post_process>` warned of an
+"unknown timestmap flag", and :meth:`MH._make_opt_mnp
+<pcapkit.protocols.internet.mh.MH._make_opt_mnp>` raised on an "invalid movile
+network prefix".
+
+Classes are imported inside each test, after
+:func:`~tests._support.reimport_once_per_class`.
+
+"""
+
+import unittest
+import warnings
+
+from tests._support import reimport_once_per_class
+
+
+class TestMessageSpelling(unittest.TestCase):
+    """Pin the spelling of the IPv4 timestamp warning and the MH prefix error."""
+
+    def setUp(self) -> None:
+        reimport_once_per_class(self)
+
+    def test_unknown_timestamp_flag_warning(self) -> None:
+        from pcapkit.const.ipv4.option_number import OptionNumber
+        from pcapkit.const.ipv4.ts_flag import TSFlag
+        from pcapkit.protocols.schema.internet.ipv4 import TSOption
+        from pcapkit.utilities.warnings import ProtocolWarning
+
+        option = TSOption(type=OptionNumber.TS, length=12, pointer=13,
+                          flags={'oflw': 0, 'flag': TSFlag.get(2)}, ts_data=[1, 2])
+        with warnings.catch_warnings(record=True) as caught:
+            warnings.simplefilter('always')
+            option.pack()
+        messages = [str(w.message) for w in caught if issubclass(w.category, ProtocolWarning)]
+        self.assertEqual(len(messages), 1, messages)
+        self.assertIn('unknown timestamp flag: 2', messages[0])
+
+    def test_invalid_mobile_network_prefix_error(self) -> None:
+        from pcapkit.const.mh.option import Option
+        from pcapkit.protocols.internet.mh import MH
+        from pcapkit.utilities.exceptions import ProtocolError
+
+        proto = object.__new__(MH)
+        with self.assertRaisesRegex(ProtocolError, "invalid mobile network prefix: '192.0.2.0/24'"):
+            proto._make_opt_mnp(Option.Mobile_Network_Prefix_Option, prefix='192.0.2.0/24')
+
+
+if __name__ == '__main__':
+    unittest.main()