diff --git a/src/mdurl/_decode.py b/src/mdurl/_decode.py
index f3edb0e..5fa8d0a 100644
--- a/src/mdurl/_decode.py
+++ b/src/mdurl/_decode.py
@@ -1,9 +1,13 @@
 from __future__ import annotations
 
-from collections.abc import Sequence
 import functools
 import re
 
+TYPE_CHECKING = False
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+
 DECODE_DEFAULT_CHARS = ";/?:@&=+$,#"
 DECODE_COMPONENT_CHARS = ""
 
diff --git a/src/mdurl/_encode.py b/src/mdurl/_encode.py
index bc2e5b9..22ca7cb 100644
--- a/src/mdurl/_encode.py
+++ b/src/mdurl/_encode.py
@@ -1,10 +1,15 @@
 from __future__ import annotations
 
-from collections.abc import Sequence
-from string import ascii_letters, digits, hexdigits
 from urllib.parse import quote as encode_uri_component
 
-ASCII_LETTERS_AND_DIGITS = ascii_letters + digits
+TYPE_CHECKING = False
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+ASCII_LETTERS_AND_DIGITS = (
+    "abcdefghijklmnopqrstuvwxyz" "ABCDEFGHIJKLMNOPQRSTUVWXYZ" "0123456789"
+)
+HEXDIGITS = "0123456789" "abcdef" "ABCDEF"
 
 ENCODE_DEFAULT_CHARS = ";/?:@&=+$,-_.!~*'()#"
 ENCODE_COMPONENT_CHARS = "-_.!~*'()"
@@ -56,7 +61,7 @@ def encode(
 
         #                              %
         if keep_escaped and code == 0x25 and i + 2 < l:
-            if all(c in hexdigits for c in string[i + 1 : i + 3]):
+            if all(c in HEXDIGITS for c in string[i + 1 : i + 3]):
                 result += string[i : i + 3]
                 i += 2
                 i += 1  # JS for loop statement3
diff --git a/src/mdurl/_format.py b/src/mdurl/_format.py
index 12524ca..83d9b13 100644
--- a/src/mdurl/_format.py
+++ b/src/mdurl/_format.py
@@ -1,7 +1,6 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
-
+TYPE_CHECKING = False
 if TYPE_CHECKING:
     from mdurl._url import URL
 
diff --git a/src/mdurl/_url.py b/src/mdurl/_url.py
index f866e7a..80624d0 100644
--- a/src/mdurl/_url.py
+++ b/src/mdurl/_url.py
@@ -1,14 +1,32 @@
 from __future__ import annotations
 
-from typing import NamedTuple
-
-
-class URL(NamedTuple):
-    protocol: str | None
-    slashes: bool
-    auth: str | None
-    port: str | None
-    hostname: str | None
-    hash: str | None  # noqa: A003
-    search: str | None
-    pathname: str | None
+from collections import namedtuple
+
+TYPE_CHECKING = False
+if TYPE_CHECKING:
+    from typing import NamedTuple
+
+    class URL(NamedTuple):
+        protocol: str | None
+        slashes: bool
+        auth: str | None
+        port: str | None
+        hostname: str | None
+        hash: str | None  # noqa: A003
+        search: str | None
+        pathname: str | None
+
+else:
+    URL = namedtuple(
+        "URL",
+        [
+            "protocol",
+            "slashes",
+            "auth",
+            "port",
+            "hostname",
+            "hash",
+            "search",
+            "pathname",
+        ],
+    )