diff --git a/src/ProxyCommands.cc b/src/ProxyCommands.cc
index c05d7a5c..3e5eb55c 100644
--- a/src/ProxyCommands.cc
+++ b/src/ProxyCommands.cc
@@ -1007,6 +1007,11 @@ static asio::awaitable<HandlerResult> S_6x(shared_ptr<Client> c, Channel::Messag
 
   bool modified = false;
   uint8_t subcommand = translate_subcommand_number(Version::BB_V4, c->version(), msg.data[0]);
+  if ((static_cast<uint8_t>(msg.data[0]) == 0xBF) && is_v1_or_v2(c->version())) {
+    c->log.warning_f("Suppressing BB-only 6xBF for V1/V2 proxy client");
+    co_return HandlerResult::SUPPRESS;
+  }
+
   switch (subcommand) {
     case 0x00:
       c->log.warning_f("Blocking invalid subcommand from server");