diff --git a/src/jsx_to_json.erl b/src/jsx_to_json.erl
index 6d8e2b8..73209eb 100644
--- a/src/jsx_to_json.erl
+++ b/src/jsx_to_json.erl
@@ -132,7 +132,9 @@ indent_or_space(Config) ->
     end.
 
 
-%% internal state is a stack of in progress objects/arrays
+%% internal state is a stack and a config object
+%%  `{Stack, Config}`
+%% the stack is a list of in progress objects/arrays
 %%  `[Current, Parent, Grandparent,...OriginalAncestor]`
 %% an object has the representation on the stack of
 %%  `{object, Object}`
diff --git a/src/jsx_to_term.erl b/src/jsx_to_term.erl
index 36fdfd0..815da4b 100644
--- a/src/jsx_to_term.erl
+++ b/src/jsx_to_term.erl
@@ -101,7 +101,9 @@ format_key(Key, Config) ->
     end.
 
 
-%% internal state is a stack of in progress objects/arrays
+%% internal state is a stack and a config object
+%%  `{Stack, Config}`
+%% the stack is a list of in progress objects/arrays
 %%  `[Current, Parent, Grandparent,...OriginalAncestor]`
 %% an object has the representation on the stack of
 %%  `{object, [{NthKey, NthValue}, {NMinus1Key, NthMinus1Value},...{FirstKey, FirstValue}]}`