diff --git a/bitlair_mqtt b/bitlair_mqtt
index 9ffd004..3d9b661 100644
--- a/bitlair_mqtt
+++ b/bitlair_mqtt
@@ -17,3 +17,11 @@ sub hook_checkout {
             for 1..$entry->quantity;
     }
 }
+
+sub hook_user_balance {
+    my ($class, $user, $old, $delta, $new, $transaction_id) = @_;
+
+    return if $user != "-cash";
+
+    $mqtt->publish("bitlair/bank/cash" => -$new);
+}