diff --git a/connection.ml b/connection.ml
index 95090b8..8660001 100644
--- a/connection.ml
+++ b/connection.ml
@@ -41,8 +41,13 @@ module Conn (C: CLIENT with type 'a Io.t = 'a Lwt.t) = struct
        match String.split_on_char '!' wh with
        | a::_ -> a
        | [] -> ""
+
   let register_callback ~prefix ~callback =
-    callbacks := (prefix,callback)::!callbacks
+    if List.mem_assoc prefix !callbacks
+    then
+      callbacks := (prefix,callback)::List.remove_assoc prefix !callbacks
+    else
+      callbacks := (prefix,callback)::!callbacks
 
   let get_command botnick msg pref =
     let nl = String.length botnick in
@@ -51,7 +56,8 @@ module Conn (C: CLIENT with type 'a Io.t = 'a Lwt.t) = struct
     if String.get msg 0 = '!' then
       (* If it's a command starting with "!" *)
       let msg = String.sub msg 1 (String.length msg - 1) in
-      if String.length msg >= n then
+      if String.length msg >= n &&
+           String.sub msg 0 n = pref then
         Some (String.sub msg n (String.length msg - n))
       else None
     else if String.length msg >= k &&
diff --git a/vantabot.ml b/vantabot.ml
index 3731bc7..d73a65d 100644
--- a/vantabot.ml
+++ b/vantabot.ml
@@ -21,7 +21,7 @@ let countdown = ref 5
 let db_file = ref "toke.db"
 
 let smolchannels = ["#tildetown"]
-let bigchannels = ["#bots";"#aaa"]
+let bigchannels = ["#bots"]
 
 let options = Arg.align
   [ "-host", Arg.Set_string host, " server host name (default: " ^ !host ^ ")"