diff --git a/net/net.c b/net/net.c
index 7576419..a609632 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1913,7 +1913,7 @@
 		sprintf(s, "%d", x & VLAN_IDMASK);
 }
 
-ushort string_to_VLAN(char *s)
+ushort string_to_VLAN(const char *s)
 {
 	ushort id;