diff --git a/.DS_Store b/.DS_Store
deleted file mode 100644
index c5a1abbe51..0000000000
Binary files a/.DS_Store and /dev/null differ
diff --git a/trustmanager/yubikey/yubikeystore.go b/trustmanager/yubikey/yubikeystore.go
index 3eacbf215d..787a6ad001 100644
--- a/trustmanager/yubikey/yubikeystore.go
+++ b/trustmanager/yubikey/yubikeystore.go
@@ -483,6 +483,12 @@ func yubiListKeys(ctx IPKCS11Ctx, session pkcs11.SessionHandle) (keys map[string
 				}
 			}
 		}
+
+		// we found nothing
+		if cert == nil {
+			continue
+		}
+
 		var ecdsaPubKey *ecdsa.PublicKey
 		switch cert.PublicKeyAlgorithm {
 		case x509.ECDSA: