diff --git a/deps/rabbit/priv/schema/rabbit.schema b/deps/rabbit/priv/schema/rabbit.schema
index f59479402b60..87fe8b47e773 100644
--- a/deps/rabbit/priv/schema/rabbit.schema
+++ b/deps/rabbit/priv/schema/rabbit.schema
@@ -889,11 +889,6 @@ end}.
 
 {mapping, "channel_max", "rabbit.channel_max", [{datatype, integer}]}.
 
-%% Set the max allowed number of channels per node.
-%% `infinity` means "no limit".
-%%
-%% {channel_max_per_node, infinity},
-
 {mapping, "channel_max_per_node", "rabbit.channel_max_per_node",
   [{datatype, [{atom, infinity}, integer]}]}.
 
diff --git a/deps/rabbit/src/rabbit_channel.erl b/deps/rabbit/src/rabbit_channel.erl
index f25ee6225196..3a7acf07dd3d 100644
--- a/deps/rabbit/src/rabbit_channel.erl
+++ b/deps/rabbit/src/rabbit_channel.erl
@@ -1318,7 +1318,7 @@ handle_method(#'basic.consume'{queue        = <<"amq.rabbitmq.reply-to">>,
               _, State = #ch{reply_consumer   = ReplyConsumer,
                              cfg = #conf{max_consumers = MaxConsumers},
                              consumer_mapping = ConsumerMapping}) ->
-    CurrentConsumers = length(maps:keys(ConsumerMapping)),
+    CurrentConsumers = maps:size(ConsumerMapping),
     case maps:find(CTag0, ConsumerMapping) of
         error when CurrentConsumers >= MaxConsumers ->  % false when MaxConsumers is 'infinity'
             rabbit_misc:protocol_error(