diff --git a/fido2/apdu.c b/fido2/apdu.c
index df89099..3d5bf49 100644
--- a/fido2/apdu.c
+++ b/fido2/apdu.c
@@ -13,7 +13,7 @@ int apdu_decode(uint8_t *data, size_t len, APDU_STRUCT *apdu)
 {
     EXT_APDU_HEADER *hapdu = (EXT_APDU_HEADER *)data;
     
-    apdu->cla = hapdu->cla;
+    apdu->cla = hapdu->cla & 0xef; // mask chaining bit if any
     apdu->ins = hapdu->ins;
     apdu->p1 = hapdu->p1;
     apdu->p2 = hapdu->p2;
diff --git a/fido2/ctap.c b/fido2/ctap.c
index 8edf591..2536c9e 100644
--- a/fido2/ctap.c
+++ b/fido2/ctap.c
@@ -1685,7 +1685,7 @@ uint8_t ctap_request(uint8_t * pkt_raw, int length, CTAP_RESPONSE * resp)
             break;
         default:
             status = CTAP1_ERR_INVALID_COMMAND;
-            printf2(TAG_ERR,"error, invalid cmd: %x\n", cmd);
+            printf2(TAG_ERR,"error, invalid cmd: 0x%02x\n", cmd);
     }
 
 done: