diff --git a/yubikit/management.py b/yubikit/management.py
index 28e14889..c9ec4cb1 100644
--- a/yubikit/management.py
+++ b/yubikit/management.py
@@ -105,7 +105,7 @@ def _from_aid(cls, aid: AID) -> "CAPABILITY":
     def display_name(self) -> str:
         if self == 0:
             return "None"
-        if f"{self:b}".count("1") > 1:
+        if bin(self).count("1") > 1:
             i = 1
             names = []
             while i < self: