diff --git a/fs/bin/add_build_info.py b/fs/bin/add_build_info.py
index 7df7cb1ad2..44316e792b 100755
--- a/fs/bin/add_build_info.py
+++ b/fs/bin/add_build_info.py
@@ -221,7 +221,7 @@ def get_platform_name():
     return sys.platform
 
 
-def alnum(v: str | bytes) -> str:
+def alnum(v):
     return "".join(v for v in filter(str.isalnum, bytestostr(v)))