diff --git a/src/lager.app.src b/src/lager.app.src
index 1936b93..6271b41 100644
--- a/src/lager.app.src
+++ b/src/lager.app.src
@@ -47,12 +47,14 @@
             {error_logger_redirect, true},
             %% How many messages per second to allow from error_logger before we start dropping them
             {error_logger_hwm, 50},
-            %% How big the gen_event mailbox can get before it is switched into sync mode
-            %% Can be reconfigured for extra sinks
+            %% How big the gen_event mailbox can get before it is
+            %% switched into sync mode.  This value only applies to
+            %% the default sink; extra sinks can supply their own.
             {async_threshold, 20},
-            %% Switch back to async mode, when gen_event mailbox size decrease from `async_threshold'
-            %% to async_threshold - async_threshold_window
-            %% Can be reconfigured for extra sinks
+            %% Switch back to async mode, when gen_event mailbox size
+            %% decrease from `async_threshold' to async_threshold -
+            %% async_threshold_window. This value only applies to the
+            %% default sink; extra sinks can supply their own.
             {async_threshold_window, 5}
         ]}
  ]}.
diff --git a/src/lager_app.erl b/src/lager_app.erl
index 0ee0fde..426ed51 100644
--- a/src/lager_app.erl
+++ b/src/lager_app.erl
@@ -112,6 +112,11 @@ start_error_logger_handler(_, HWM, {ok, WhiteList}) ->
             []
     end.
 
+%% `determine_async_behavior/3' is called with the results from either
+%% `application:get_env/2' and `proplists:get_value/2'. Since
+%% `application:get_env/2' wraps a successful retrieval in an `{ok,
+%% Value}' tuple, do the same for the result from
+%% `proplists:get_value/2'.
 wrap_proplist_value(undefined) ->
     undefined;
 wrap_proplist_value(Value) ->