diff --git a/client/src/cmdhfmf.c b/client/src/cmdhfmf.c
index 102289f8c..398205d6d 100644
--- a/client/src/cmdhfmf.c
+++ b/client/src/cmdhfmf.c
@@ -5367,7 +5367,7 @@ static int CmdHF14AMfMAD(const char *Cmd) {
         }
 
         // MAD detection
-        if (HasMADKey(dump)) {
+        if (HasMADKey(dump) == false) {
             PrintAndLogEx(FAILED, "No MAD key was detected in the dump file");
             free(dump);
             return PM3_ESOFT;
diff --git a/client/src/mifare/mad.c b/client/src/mifare/mad.c
index 1e42cd2e1..759f5540a 100644
--- a/client/src/mifare/mad.c
+++ b/client/src/mifare/mad.c
@@ -402,5 +402,5 @@ bool HasMADKey(uint8_t *d) {
     if (d == NULL)
         return false;
 
-    return (memcmp(d + (3 * MFBLOCK_SIZE), g_mifare_mad_key, 6) != 0);
+    return (memcmp(d + (3 * MFBLOCK_SIZE), g_mifare_mad_key, sizeof(g_mifare_mad_key)) == 0);
 }
\ No newline at end of file