diff --git a/stdlib/codecs.pyi b/stdlib/codecs.pyi
index 1a596b95a..ad4f74357 100644
--- a/stdlib/codecs.pyi
+++ b/stdlib/codecs.pyi
@@ -82,8 +82,10 @@ def decode(obj: str, encoding: Literal["rot13", "rot_13"] = ..., errors: str = .
 @overload
 def decode(obj: _Encoded, encoding: str = ..., errors: str = ...) -> _Decoded: ...
 def lookup(__encoding: str) -> CodecInfo: ...
-def utf_16_be_decode(__obj: _Encoded, __errors: str = ..., __final: bool = ...) -> Tuple[_Decoded, int]: ...  # undocumented
-def utf_16_be_encode(__obj: _Decoded, __errors: str = ...) -> Tuple[_Encoded, int]: ...  # undocumented
+def utf_16_be_decode(
+    __data: _Encoded, __errors: Optional[str] = ..., __final: bool = ...
+) -> Tuple[_Decoded, int]: ...  # undocumented
+def utf_16_be_encode(__str: _Decoded, __errors: Optional[str] = ...) -> Tuple[_Encoded, int]: ...  # undocumented
 
 class CodecInfo(Tuple[_Encoder, _Decoder, _StreamReader, _StreamWriter]):
     @property
@@ -160,7 +162,7 @@ class IncrementalEncoder:
     errors: str
     def __init__(self, errors: str = ...) -> None: ...
     @abstractmethod
-    def encode(self, object: _Decoded, final: bool = ...) -> _Encoded: ...
+    def encode(self, input: _Decoded, final: bool = ...) -> _Encoded: ...
     def reset(self) -> None: ...
     # documentation says int but str is needed for the subclass.
     def getstate(self) -> Union[int, _Decoded]: ...
@@ -188,7 +190,7 @@ class BufferedIncrementalDecoder(IncrementalDecoder):
     def __init__(self, errors: str = ...) -> None: ...
     @abstractmethod
     def _buffer_decode(self, input: _Encoded, errors: str, final: bool) -> Tuple[_Decoded, int]: ...
-    def decode(self, object: _Encoded, final: bool = ...) -> _Decoded: ...
+    def decode(self, input: _Encoded, final: bool = ...) -> _Decoded: ...
 
 _SW = TypeVar("_SW", bound=StreamWriter)
 
@@ -197,14 +199,14 @@ _SW = TypeVar("_SW", bound=StreamWriter)
 class StreamWriter(Codec):
     errors: str
     def __init__(self, stream: IO[_Encoded], errors: str = ...) -> None: ...
-    def write(self, obj: _Decoded) -> None: ...
+    def write(self, object: _Decoded) -> None: ...
     def writelines(self, list: Iterable[_Decoded]) -> None: ...
     def reset(self) -> None: ...
     def __enter__(self: _SW) -> _SW: ...
     def __exit__(
         self, typ: Optional[Type[BaseException]], exc: Optional[BaseException], tb: Optional[types.TracebackType]
     ) -> None: ...
-    def __getattr__(self, name: str) -> Any: ...
+    def __getattr__(self, name: str, getattr: Callable[[str], Any] = ...) -> Any: ...
 
 _SR = TypeVar("_SR", bound=StreamReader)
 
@@ -212,15 +214,15 @@ class StreamReader(Codec):
     errors: str
     def __init__(self, stream: IO[_Encoded], errors: str = ...) -> None: ...
     def read(self, size: int = ..., chars: int = ..., firstline: bool = ...) -> _Decoded: ...
-    def readline(self, size: int = ..., keepends: bool = ...) -> _Decoded: ...
-    def readlines(self, sizehint: int = ..., keepends: bool = ...) -> List[_Decoded]: ...
+    def readline(self, size: Optional[int] = ..., keepends: bool = ...) -> _Decoded: ...
+    def readlines(self, sizehint: Optional[int] = ..., keepends: bool = ...) -> List[_Decoded]: ...
     def reset(self) -> None: ...
     def __enter__(self: _SR) -> _SR: ...
     def __exit__(
         self, typ: Optional[Type[BaseException]], exc: Optional[BaseException], tb: Optional[types.TracebackType]
     ) -> None: ...
     def __iter__(self) -> Iterator[_Decoded]: ...
-    def __getattr__(self, name: str) -> Any: ...
+    def __getattr__(self, name: str, getattr: Callable[[str], Any] = ...) -> Any: ...
 
 _T = TypeVar("_T", bound=StreamReaderWriter)
 
diff --git a/tests/stubtest_whitelists/py36.txt b/tests/stubtest_whitelists/py36.txt
index d76c12b05..b454d8ad8 100644
--- a/tests/stubtest_whitelists/py36.txt
+++ b/tests/stubtest_whitelists/py36.txt
@@ -13,7 +13,6 @@ asyncio.threads  # Added in Python 3.9
 asyncio.trsock  # Added in Python 3.8
 builtins.str.maketrans
 cmath.log
-codecs.StreamRecoder.seek
 collections.AsyncGenerator.ag_await
 collections.AsyncGenerator.ag_code
 collections.AsyncGenerator.ag_frame
diff --git a/tests/stubtest_whitelists/py3_common.txt b/tests/stubtest_whitelists/py3_common.txt
index cd6f93bbc..4dd34ace9 100644
--- a/tests/stubtest_whitelists/py3_common.txt
+++ b/tests/stubtest_whitelists/py3_common.txt
@@ -85,21 +85,13 @@ bz2.BZ2File.writelines
 cgi.FieldStorage.__init__
 cgi.parse
 cgi.parse_multipart
-codecs.BufferedIncrementalDecoder.decode
+# The following CodecInfo properties are added in __new__
 codecs.CodecInfo.decode
 codecs.CodecInfo.encode
 codecs.CodecInfo.incrementaldecoder
 codecs.CodecInfo.incrementalencoder
 codecs.CodecInfo.streamreader
 codecs.CodecInfo.streamwriter
-codecs.IncrementalEncoder.encode
-codecs.StreamReader.__getattr__
-codecs.StreamReader.readline
-codecs.StreamReader.readlines
-codecs.StreamWriter.__getattr__
-codecs.StreamWriter.write
-codecs.utf_16_be_decode
-codecs.utf_16_be_encode
 collections.Callable
 collections.ChainMap.get
 collections.ChainMap.maps