diff --git a/src/structlog/contextvars.py b/src/structlog/contextvars.py
index 75bfec83..835b6264 100644
--- a/src/structlog/contextvars.py
+++ b/src/structlog/contextvars.py
@@ -24,15 +24,15 @@
 
 from collections.abc import Generator, Mapping
 from types import FrameType
-from typing import Any
+from typing import Any, Final
 
 import structlog
 
 from .typing import BindableLogger, EventDict, WrappedLogger
 
 
-STRUCTLOG_KEY_PREFIX = "structlog_"
-STRUCTLOG_KEY_PREFIX_LEN = len(STRUCTLOG_KEY_PREFIX)
+STRUCTLOG_KEY_PREFIX: Final = "structlog_"
+STRUCTLOG_KEY_PREFIX_LEN: Final = len(STRUCTLOG_KEY_PREFIX)
 
 _ASYNC_CALLING_STACK: contextvars.ContextVar[FrameType] = (
     contextvars.ContextVar("_ASYNC_CALLING_STACK")
diff --git a/src/structlog/dev.py b/src/structlog/dev.py
index 7cef73f6..8ab25d15 100644
--- a/src/structlog/dev.py
+++ b/src/structlog/dev.py
@@ -468,7 +468,7 @@ def __call__(self, sio: TextIO, exc_info: ExcInfo) -> None:
 
 if rich is None:
 
-    def rich_traceback(*args, **kw):
+    def rich_traceback(sio: TextIO, exc_info: ExcInfo) -> None:
         raise ModuleNotFoundError(
             "RichTracebackFormatter requires Rich to be installed.",
             name="rich",
diff --git a/src/structlog/processors.py b/src/structlog/processors.py
index 20e6e1f2..8eefaecc 100644
--- a/src/structlog/processors.py
+++ b/src/structlog/processors.py
@@ -24,6 +24,7 @@
 from typing import (
     Any,
     ClassVar,
+    Final,
     NamedTuple,
     TextIO,
     cast,
@@ -424,7 +425,7 @@ def __call__(
         return event_dict
 
 
-format_exc_info = ExceptionRenderer()
+format_exc_info: Final = ExceptionRenderer()
 """
 Replace an ``exc_info`` field with an ``exception`` string field using Python's
 built-in traceback formatting.
@@ -445,7 +446,7 @@ def __call__(
     features.
 """
 
-dict_tracebacks = ExceptionRenderer(ExceptionDictTransformer())
+dict_tracebacks: Final = ExceptionRenderer(ExceptionDictTransformer())
 """
 Replace an ``exc_info`` field with an ``exception`` field containing structured
 tracebacks suitable for, e.g., JSON output.
diff --git a/src/structlog/threadlocal.py b/src/structlog/threadlocal.py
index c712f551..f8dba786 100644
--- a/src/structlog/threadlocal.py
+++ b/src/structlog/threadlocal.py
@@ -21,7 +21,7 @@
 import warnings
 
 from collections.abc import Generator, Iterator
-from typing import Any, TypeVar
+from typing import Any, Final, TypeVar
 
 import structlog
 
@@ -44,7 +44,7 @@ def _determine_threadlocal() -> type[Any]:
     return GreenThreadLocal  # pragma: no cover
 
 
-ThreadLocal = _determine_threadlocal()
+ThreadLocal: Final[type] = _determine_threadlocal()
 
 
 def _deprecated() -> None: