diff --git a/fido2/apdu.c b/fido2/apdu.c
index b2516ea..2e8123f 100644
--- a/fido2/apdu.c
+++ b/fido2/apdu.c
@@ -44,8 +44,8 @@ int apdu_decode(uint8_t *data, size_t len, APDU_STRUCT *apdu)
     // case 3S (Lc + data)
     if (len == 5U + b0 && b0 != 0)
     {
-        apdu->case_type = 0x13;
-        apdu->lc = (hapdu->lc[1] << 8) + hapdu->lc[2];
+        apdu->case_type = 0x03;
+        apdu->lc = b0;
     }
     
     // case 4S (Lc + data + Le)
diff --git a/targets/stm32l432/src/nfc.c b/targets/stm32l432/src/nfc.c
index 9a2a859..54c3859 100644
--- a/targets/stm32l432/src/nfc.c
+++ b/targets/stm32l432/src/nfc.c
@@ -440,12 +440,24 @@ void nfc_process_iblock(uint8_t * buf, int len)
     int status;
     uint16_t reslen;
     
-    APDU_STRUCT apdu;
-    apdu_decode(buf + 1, len - 1, &apdu);
-
     printf1(TAG_NFC,"Iblock: ");
 	dump_hex1(TAG_NFC, buf, len);
 
+    uint8_t apdu_offset = 1;
+    // NAD following
+    if (buf[0] & 0x04) apdu_offset++;
+    // CID following
+    if (buf[0] & 0x08) apdu_offset++;
+
+    APDU_STRUCT apdu;
+    if (apdu_decode(buf + apdu_offset, len - apdu_offset, &apdu)) {
+        printf1(TAG_NFC,"apdu decode error\n");
+        nfc_write_response(buf[0], SW_COND_USE_NOT_SATISFIED);
+        return;
+    }
+    printf1(TAG_NFC,"apdu ok. %scase=%02x cla=%02x ins=%02x p1=%02x p2=%02x lc=%d le=%d\n", 
+        apdu.extended_apdu ? "[e]":"", apdu.case_type, apdu.cla, apdu.ins, apdu.p1, apdu.p2, apdu.lc, apdu.le);
+
     // TODO this needs to be organized better
     switch(apdu.ins)
     {