diff --git a/bffhd/authentication/fabfire_bin/server.rs b/bffhd/authentication/fabfire_bin/server.rs
index e183f2b..48077aa 100644
--- a/bffhd/authentication/fabfire_bin/server.rs
+++ b/bffhd/authentication/fabfire_bin/server.rs
@@ -361,8 +361,7 @@ impl Authentication for FabFire {
                     Ok(_) => {
                         match apdu_response.body {
                             Some(data) => {
-                                let authid = String::from_utf8(data)
-                                    .unwrap()
+                                let authid = hex::encode(data)
                                     .trim_matches(char::from(0))
                                     .to_string();
                                 let prov = ThisProvider::<AuthId>::with(&authid);