diff --git a/client/src/cmdhfmfp.c b/client/src/cmdhfmfp.c
index cd6126cd4..4215718b5 100644
--- a/client/src/cmdhfmfp.c
+++ b/client/src/cmdhfmfp.c
@@ -227,7 +227,7 @@ static int mfp_load_keys(uint8_t **pkeyBlock, uint32_t *pkeycnt, uint8_t *userke
 
             int len = hex_to_bytes(g_mifare_plus_default_keys[cnt], (uint8_t *)(*pkeyBlock + (*pkeycnt + cnt) * AES_KEY_LEN), AES_KEY_LEN);
 
-            PrintAndLogEx(DEBUG, _YELLOW_("%2u") " - %s", (*pkeycnt + cnt), sprint_hex_inrow(*pkeyBlock + (*pkeycnt + cnt) * AES_KEY_LEN, AES_KEY_LEN));
+            PrintAndLogEx(DEBUG, _YELLOW_("%2zu") " - %s", (*pkeycnt + cnt), sprint_hex_inrow(*pkeyBlock + (*pkeycnt + cnt) * AES_KEY_LEN, AES_KEY_LEN));
             if (len != AES_KEY_LEN) {
                 break;
             }