--- a/vehicle.c	Tue May 17 20:54:05 2005 +0000
+++ b/vehicle.c	Tue May 17 20:58:58 2005 +0000
@@ -1654,7 +1654,7 @@
 	Vehicle *v;
 	StringID str;
 
-	if (!IsVehicleIndex(p1)) return CMD_ERROR;
+	if (!IsVehicleIndex(p1) || _cmd_text[0] == '\0') return CMD_ERROR;
 
 	v = GetVehicle(p1);