diff --git a/www/board/agenda/daemon/channel.rb b/www/board/agenda/daemon/channel.rb
index 3b609ad88e..b26491ea5a 100644
--- a/www/board/agenda/daemon/channel.rb
+++ b/www/board/agenda/daemon/channel.rb
@@ -15,7 +15,7 @@
 
 class Channel
   @@sockets = Concurrent::Map.new
-  @@users = Concurrent::Map.new {|map,key| map[key]=[]}
+  @@users = Concurrent::Map.new {|map,key| map.compute_if_absent(key) { [] } }
 
   begin
     FOUNDATION_BOARD = ASF::SVN['foundation_board']