diff --git a/apps/emqx/src/emqx_authentication.erl b/apps/emqx/src/emqx_authentication.erl
index b8476de56..2e53d85eb 100644
--- a/apps/emqx/src/emqx_authentication.erl
+++ b/apps/emqx/src/emqx_authentication.erl
@@ -226,7 +226,7 @@ do_pre_config_update({move_authenticator, _ChainName, AuthenticatorID, Position}
             end
     end.
 
--spec post_config_update(update_request, map() | list(), emqx_config:raw_config(), emqx_config:app_envs())
+-spec post_config_update(update_request(), map() | list(), emqx_config:raw_config(), emqx_config:app_envs())
     -> ok | {ok, map()} | {error, term()}.
 post_config_update(UpdateReq, NewConfig, OldConfig, AppEnvs) ->
     do_post_config_update(UpdateReq, check_config(to_list(NewConfig)), OldConfig, AppEnvs).
diff --git a/apps/emqx_authn/src/simple_authn/emqx_authn_http.erl b/apps/emqx_authn/src/simple_authn/emqx_authn_http.erl
index 5495b139a..daa7f8073 100644
--- a/apps/emqx_authn/src/simple_authn/emqx_authn_http.erl
+++ b/apps/emqx_authn/src/simple_authn/emqx_authn_http.erl
@@ -214,7 +214,7 @@ default_headers_no_content_type() ->
 
 transform_header_name(Headers) ->
     maps:fold(fun(K0, V, Acc) ->
-                  K = list_to_binary(string:to_lower(binary_to_list(K0))),
+                  K = list_to_binary(string:to_lower(to_list(K0))),
                   maps:put(K, V, Acc)
               end, #{}, Headers).
 
@@ -301,3 +301,8 @@ parse_body(<<"application/x-www-form-urlencoded">>, Body) ->
     {ok, maps:from_list(cow_qs:parse_qs(Body))};
 parse_body(ContentType, _) ->
     {error, {unsupported_content_type, ContentType}}.
+
+to_list(A) when is_atom(A) ->
+    atom_to_list(A);
+to_list(B) when is_binary(B) ->
+    binary_to_list(B).
diff --git a/apps/emqx_authz/src/emqx_authz_schema.erl b/apps/emqx_authz/src/emqx_authz_schema.erl
index b90d522e8..b3915b7c0 100644
--- a/apps/emqx_authz/src/emqx_authz_schema.erl
+++ b/apps/emqx_authz/src/emqx_authz_schema.erl
@@ -66,7 +66,7 @@ fields(http_get) ->
                               },
                   converter => fun (Headers0) ->
                                     Headers1 = maps:fold(fun(K0, V, AccIn) ->
-                                                           K1 = iolist_to_binary(string:to_lower(binary_to_list(K0))),
+                                                           K1 = iolist_to_binary(string:to_lower(to_list(K0))),
                                                            maps:put(K1, V, AccIn)
                                                         end, #{}, Headers0),
                                     maps:merge(#{ <<"accept">> => <<"application/json">>
@@ -177,3 +177,8 @@ connector_fields(DB, Fields) ->
     , {enable, #{type => boolean(),
                  default => true}}
     ] ++ Mod:fields(Fields).
+
+to_list(A) when is_atom(A) ->
+    atom_to_list(A);
+to_list(B) when is_binary(B) ->
+    binary_to_list(B).
\ No newline at end of file