diff --git a/server/verify.py b/server/verify.py
index da880f4..5686d77 100644
--- a/server/verify.py
+++ b/server/verify.py
@@ -3,9 +3,13 @@
 from server.base import BadRequestException
 
 
+_invalid_category = {"Cf", "Mn"}
+
+
 def check_invalid_input_str(*s: str) -> None:
     for ss in s:
         for c in ss:
             v = unicodedata.category(c)
-            if v == "Cf":  # Format
+            print(repr(c), v)
+            if v in _invalid_category:  # Format
                 raise BadRequestException("invalid character {!r}".format(c))