diff --git a/armsrc/iso14443a.c b/armsrc/iso14443a.c
index d02ad8850..60bc0cd70 100644
--- a/armsrc/iso14443a.c
+++ b/armsrc/iso14443a.c
@@ -2606,7 +2606,7 @@ void DetectNACKbug() {
 
 		// Test if the action was cancelled
 		if(BUTTON_PRESS()) {
-			isOK = -1;
+			isOK = 99;
 			break;
 		}
 		
@@ -2675,7 +2675,7 @@ void DetectNACKbug() {
 					unexpected_random++;
 					if (unexpected_random > MAX_UNEXPECTED_RANDOM) {
 						// Card has an unpredictable PRNG. Give up	
-						isOK = -3;
+						isOK = 98;
 						break;
 					} else {						
 						if (sync_cycles <= 0) {
@@ -2687,7 +2687,7 @@ void DetectNACKbug() {
 				}
 				
 				if (++sync_tries > MAX_SYNC_TRIES) {
-					isOK = -4; 			// Card's PRNG runs at an unexpected frequency or resets unexpectedly
+					isOK = 97; 			// Card's PRNG runs at an unexpected frequency or resets unexpectedly
 					break;
 				}
 				
@@ -2697,7 +2697,7 @@ void DetectNACKbug() {
 					sync_cycles += PRNG_SEQUENCE_LENGTH;
 				
 				if (sync_cycles > PRNG_SEQUENCE_LENGTH * 2 ) {
-					isOK = -4; 			// Card's PRNG runs at an unexpected frequency or resets unexpectedly
+					isOK = 96; 			// Card's PRNG runs at an unexpected frequency or resets unexpectedly
 					break;
 				}
 				
diff --git a/client/cmdhf14a.c b/client/cmdhf14a.c
index 17a745f45..27e4d3879 100644
--- a/client/cmdhf14a.c
+++ b/client/cmdhf14a.c
@@ -166,6 +166,7 @@ int usage_hf_14a_info(void){
 	PrintAndLog("This command makes more extensive tests against a ISO14443a tag in order to collect information");
 	PrintAndLog("Usage: hf 14a info [h|s]");
 	PrintAndLog("       s    silent (no messages)");
+	PrintAndLog("       n    test for nack bug");
 	return 0;
 }
 
@@ -274,6 +275,8 @@ int CmdHF14AInfo(const char *Cmd) {
 	if (Cmd[0] == 'h' || Cmd[0] ==  'H') return usage_hf_14a_info();
 	
 	bool silent = (Cmd[0] == 's' || Cmd[0] ==  'S');
+	bool do_nack_test = (Cmd[0] == 'n' || Cmd[0] ==  'N');
+	
 	UsbCommand c = {CMD_READER_ISO_14443a, {ISO14A_CONNECT | ISO14A_NO_DISCONNECT, 0, 0}};
 	clearCommandBuffer();
 	SendCommand(&c);
@@ -494,7 +497,10 @@ int CmdHF14AInfo(const char *Cmd) {
 		if ( detect_classic_prng() )
 			PrintAndLog("Prng detection: WEAK");
 		else
-			PrintAndLog("Prng detection: HARDEND (hardnested)");		
+			PrintAndLog("Prng detection: HARDEND (hardnested)");
+		
+		if ( do_nack_test )
+			detect_classic_nackbug(silent);
 	}
 	
 	return select_status;
diff --git a/client/mifarehost.c b/client/mifarehost.c
index 82f62a016..3258aea0b 100644
--- a/client/mifarehost.c
+++ b/client/mifarehost.c
@@ -890,13 +890,15 @@ int detect_classic_nackbug(bool verbose){
 				PrintAndLog("Num of received NACK  : %u", nacks);
 			}
 			switch( ok ) {
-				case -1 : if (verbose) PrintAndLog("Button pressed. Aborted."); return 0;
-				case -3 : if (verbose) PrintAndLog("Card random number generator is not predictable)."); return 0;
-				case -4 : if (verbose) {
+				case 99 : if (verbose) PrintAndLog("Button pressed. Aborted."); return 0;
+				case 96 : 
+				case 98 : if (verbose) PrintAndLog("Card random number generator is not predictable)."); return 0;
+				case 97 : if (verbose) {
 							PrintAndLog("Card random number generator seems to be based on the well-known generating polynomial");
 							PrintAndLog("with 16 effective bits only, but shows unexpected behavior, try again."); 
 							return 0;
 						}
+				
 				case  2 : PrintAndLog("Always leak NACK detected"); return 3;
 				case  1 : PrintAndLog("NACK bug detected"); return 1;
 				case  0 : PrintAndLog("No NACK bug detected"); return 2;