diff --git a/mdmon.c b/mdmon.c
index f0b0623..8cd53d8 100644
--- a/mdmon.c
+++ b/mdmon.c
@@ -320,7 +320,7 @@ int main(int argc, char *argv[])
 			dofork = 0;
 			break;
 		case OffRootOpt:
-			/* silently ignore old option */
+			argv[0][0] = '@';
 			break;
 		case 'h':
 		default: