diff --git a/client/cmdhfmfu.c b/client/cmdhfmfu.c
index c7de6c7dc..cc2e05d6b 100644
--- a/client/cmdhfmfu.c
+++ b/client/cmdhfmfu.c
@@ -1681,7 +1681,7 @@ int CmdHF14AMfucAuth(const char *Cmd){
 	//Change key to user defined one
 	if (cmdp == 'k' || cmdp == 'K'){
 		keyNo = param_get8(Cmd, 1);
-		if(keyNo > KEYS_3DES_COUNT) 
+		if(keyNo >= KEYS_3DES_COUNT) 
 			errors = true;
 	}