diff --git a/stdlib/unicodedata.pyi b/stdlib/unicodedata.pyi
index 7337ab8789b2..5a9aa0a3395f 100644
--- a/stdlib/unicodedata.pyi
+++ b/stdlib/unicodedata.pyi
@@ -1,4 +1,5 @@
 import sys
+from _typeshed import ReadOnlyBuffer
 from typing import Any, TypeVar
 from typing_extensions import final
 
@@ -21,7 +22,7 @@ def east_asian_width(__chr: str) -> str: ...
 if sys.version_info >= (3, 8):
     def is_normalized(__form: str, __unistr: str) -> bool: ...
 
-def lookup(__name: str | bytes) -> str: ...
+def lookup(__name: str | ReadOnlyBuffer) -> str: ...
 def mirrored(__chr: str) -> int: ...
 def name(__chr: str, __default: _T = ...) -> str | _T: ...
 def normalize(__form: str, __unistr: str) -> str: ...
@@ -41,7 +42,7 @@ class UCD:
     if sys.version_info >= (3, 8):
         def is_normalized(self, __form: str, __unistr: str) -> bool: ...
 
-    def lookup(self, __name: str | bytes) -> str: ...
+    def lookup(self, __name: str | ReadOnlyBuffer) -> str: ...
     def mirrored(self, __chr: str) -> int: ...
     def name(self, __chr: str, __default: _T = ...) -> str | _T: ...
     def normalize(self, __form: str, __unistr: str) -> str: ...