diff --git a/pcapkit/protocols/application/ftp.py b/pcapkit/protocols/application/ftp.py
index ef955bd087..984f781798 100644
--- a/pcapkit/protocols/application/ftp.py
+++ b/pcapkit/protocols/application/ftp.py
@@ -291,48 +291,6 @@ def _make_data(cls, data: 'Data_FTP') -> 'dict[str, Any]':  # type: ignore[overr
             'lines': getattr(data, 'lines', ()),
         }
 
-    @staticmethod
-    def _make_code(code: 'Enum_ReturnCode | int | str | bytes | bytearray') -> 'bytes':
-        """Render a reply code as the three digits a reply line opens with.
-
-        The three digits hold ``0``--``999``, which is what the ``[0-9]{3}``
-        of ``FTP_RESPONSE`` reads back, so that is the range accepted rather
-        than the 1xx--5xx of :rfc:`959#section-4.2` alone -- 6xx is
-        :rfc:`2228#section-5`, and the read path accepts it.
-
-        Args:
-            code: Reply code, an :class:`int` (a
-                :class:`~pcapkit.const.ftp.return_code.ReturnCode` member is
-                one) or a numeric :class:`str`, :class:`bytes` or
-                :class:`bytearray` holding one.
-
-        Returns:
-            The code as three digits, a leading zero kept.
-
-        Raises:
-            ProtocolError: If ``code`` is of any other type, a :obj:`bool`
-                included, or does not fit in three digits.
-
-        """
-        # NOTE: ``ReturnCode`` is an ``IntEnum``, so a member takes the ``int``
-        # branch. ``bool`` is an ``int`` subclass, so without the explicit check
-        # ``True`` would write code 001, and ``int()`` alone would raise a bare
-        # ValueError or TypeError rather than a ProtocolError (#2416).
-        value = None  # type: Optional[int]
-        if isinstance(code, bool):
-            pass
-        elif isinstance(code, int):
-            value = code
-        elif isinstance(code, (str, bytes, bytearray)):
-            try:
-                value = int(code)
-            except ValueError:
-                pass
-        if value is None or not 0 <= value <= 999:
-            raise ProtocolError('FTP: invalid status code: must be an int in 0-999 or a '
-                                f'numeric str, bytes or bytearray, not {code!r}')
-        return b'%03d' % value
-
     @staticmethod
     def _test_lines(code: 'bytes', lines: 'tuple[bytes, ...]') -> 'bool':
         """Whether ``lines`` are the rest of a multi-line reply with ``code``.
@@ -383,3 +341,45 @@ def _decode_args(self, args: 'Optional[bytes]') -> 'tuple[Optional[str], Optiona
             except (LookupError, UnicodeError):
                 pass
         return args.decode('latin-1'), 'latin-1'
+
+    @staticmethod
+    def _make_code(code: 'Enum_ReturnCode | int | str | bytes | bytearray') -> 'bytes':
+        """Render a reply code as the three digits a reply line opens with.
+
+        The three digits hold ``0``--``999``, which is what the ``[0-9]{3}``
+        of ``FTP_RESPONSE`` reads back, so that is the range accepted rather
+        than the 1xx--5xx of :rfc:`959#section-4.2` alone -- 6xx is
+        :rfc:`2228#section-5`, and the read path accepts it.
+
+        Args:
+            code: Reply code, an :class:`int` (a
+                :class:`~pcapkit.const.ftp.return_code.ReturnCode` member is
+                one) or a numeric :class:`str`, :class:`bytes` or
+                :class:`bytearray` holding one.
+
+        Returns:
+            The code as three digits, a leading zero kept.
+
+        Raises:
+            ProtocolError: If ``code`` is of any other type, a :obj:`bool`
+                included, or does not fit in three digits.
+
+        """
+        # NOTE: ``ReturnCode`` is an ``IntEnum``, so a member takes the ``int``
+        # branch. ``bool`` is an ``int`` subclass, so without the explicit check
+        # ``True`` would write code 001, and ``int()`` alone would raise a bare
+        # ValueError or TypeError rather than a ProtocolError (#2416).
+        value = None  # type: Optional[int]
+        if isinstance(code, bool):
+            pass
+        elif isinstance(code, int):
+            value = code
+        elif isinstance(code, (str, bytes, bytearray)):
+            try:
+                value = int(code)
+            except ValueError:
+                pass
+        if value is None or not 0 <= value <= 999:
+            raise ProtocolError('FTP: invalid status code: must be an int in 0-999 or a '
+                                f'numeric str, bytes or bytearray, not {code!r}')
+        return b'%03d' % value