diff --git a/src/tomli/_parser.py b/src/tomli/_parser.py
index db56a16..b548e8b 100644
--- a/src/tomli/_parser.py
+++ b/src/tomli/_parser.py
@@ -32,25 +32,25 @@
 # lower number than where mypyc binaries crash.
 MAX_INLINE_NESTING: Final = sys.getrecursionlimit()
 
-ASCII_CTRL = frozenset(chr(i) for i in range(32)) | frozenset(chr(127))
+ASCII_CTRL: Final = frozenset(chr(i) for i in range(32)) | frozenset(chr(127))
 
 # Neither of these sets include quotation mark or backslash. They are
 # currently handled as separate cases in the parser functions.
-ILLEGAL_BASIC_STR_CHARS = ASCII_CTRL - frozenset("\t")
-ILLEGAL_MULTILINE_BASIC_STR_CHARS = ASCII_CTRL - frozenset("\t\n")
+ILLEGAL_BASIC_STR_CHARS: Final = ASCII_CTRL - frozenset("\t")
+ILLEGAL_MULTILINE_BASIC_STR_CHARS: Final = ASCII_CTRL - frozenset("\t\n")
 
-ILLEGAL_LITERAL_STR_CHARS = ILLEGAL_BASIC_STR_CHARS
-ILLEGAL_MULTILINE_LITERAL_STR_CHARS = ILLEGAL_MULTILINE_BASIC_STR_CHARS
+ILLEGAL_LITERAL_STR_CHARS: Final = ILLEGAL_BASIC_STR_CHARS
+ILLEGAL_MULTILINE_LITERAL_STR_CHARS: Final = ILLEGAL_MULTILINE_BASIC_STR_CHARS
 
-ILLEGAL_COMMENT_CHARS = ILLEGAL_BASIC_STR_CHARS
+ILLEGAL_COMMENT_CHARS: Final = ILLEGAL_BASIC_STR_CHARS
 
-TOML_WS = frozenset(" \t")
-TOML_WS_AND_NEWLINE = TOML_WS | frozenset("\n")
-BARE_KEY_CHARS = frozenset(string.ascii_letters + string.digits + "-_")
-KEY_INITIAL_CHARS = BARE_KEY_CHARS | frozenset("\"'")
-HEXDIGIT_CHARS = frozenset(string.hexdigits)
+TOML_WS: Final = frozenset(" \t")
+TOML_WS_AND_NEWLINE: Final = TOML_WS | frozenset("\n")
+BARE_KEY_CHARS: Final = frozenset(string.ascii_letters + string.digits + "-_")
+KEY_INITIAL_CHARS: Final = BARE_KEY_CHARS | frozenset("\"'")
+HEXDIGIT_CHARS: Final = frozenset(string.hexdigits)
 
-BASIC_STR_ESCAPE_REPLACEMENTS = MappingProxyType(
+BASIC_STR_ESCAPE_REPLACEMENTS: Final = MappingProxyType(
     {
         "\\b": "\u0008",  # backspace
         "\\t": "\u0009",  # tab
diff --git a/src/tomli/_re.py b/src/tomli/_re.py
index 9eacefc..5134866 100644
--- a/src/tomli/_re.py
+++ b/src/tomli/_re.py
@@ -7,16 +7,18 @@
 from datetime import date, datetime, time, timedelta, timezone, tzinfo
 from functools import lru_cache
 import re
-from typing import Any
+from typing import Any, Final
 
 from ._types import ParseFloat
 
 # E.g.
 # - 00:32:00.999999
 # - 00:32:00
-_TIME_RE_STR = r"([01][0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9])(?:\.([0-9]{1,6})[0-9]*)?"
+_TIME_RE_STR: Final = (
+    r"([01][0-9]|2[0-3]):([0-5][0-9]):([0-5][0-9])(?:\.([0-9]{1,6})[0-9]*)?"
+)
 
-RE_NUMBER = re.compile(
+RE_NUMBER: Final = re.compile(
     r"""
 0
 (?:
@@ -35,8 +37,8 @@
 """,
     flags=re.VERBOSE,
 )
-RE_LOCALTIME = re.compile(_TIME_RE_STR)
-RE_DATETIME = re.compile(
+RE_LOCALTIME: Final = re.compile(_TIME_RE_STR)
+RE_DATETIME: Final = re.compile(
     rf"""
 ([0-9]{{4}})-(0[1-9]|1[0-2])-(0[1-9]|[12][0-9]|3[01])  # date, e.g. 1988-10-27
 (?: