diff --git a/proto/connections/offline_wire_formats.proto b/proto/connections/offline_wire_formats.proto
index 43762f86..5e582539 100644
--- a/proto/connections/offline_wire_formats.proto
+++ b/proto/connections/offline_wire_formats.proto
@@ -191,6 +191,7 @@ message BandwidthUpgradeNegotiationFrame {
       optional string password = 2;
       optional int32 port = 3;
       optional string gateway = 4 [default = "0.0.0.0"];
+      optional int32 frequency = 5 [default = -1];
     }
 
     // Accompanies Medium.WIFI_LAN.