diff --git a/main.c b/main.c
index 9f3f392..d460835 100644
--- a/main.c
+++ b/main.c
@@ -445,6 +445,7 @@ int main(int argc, char *argv[])
 				failure("Extra characters after ramsize: \'%s\'\n", endptr);
 			break;
 		case 'N':
+			nice_set = true;
 			control->nice_val = strtol(optarg, &endptr, 10);
 			if (control->nice_val < PRIO_MIN || control->nice_val > PRIO_MAX)
 				failure("Invalid nice value (must be %d...%d)\n", PRIO_MIN, PRIO_MAX);