diff --git a/src/woody.erl b/src/woody.erl
index 3d5f936..2547382 100644
--- a/src/woody.erl
+++ b/src/woody.erl
@@ -46,7 +46,7 @@
 -export_type([handler/1, ev_handler/0, options/0]).
 
 -type role()                :: client | server.
--type url()                 :: string(). %% http://erlang.org/doc/man/httpc.html#http-data-types
+-type url()                 :: binary() | string().
 -type path()                :: '_' | iodata(). %% cowboy_router:route_match()
 -type http_handler(Handler) :: {path(), Handler}.
 -export_type([role/0, url/0, path/0, http_handler/1]).
diff --git a/src/woody_resolver.erl b/src/woody_resolver.erl
index 7719052..9c98454 100644
--- a/src/woody_resolver.erl
+++ b/src/woody_resolver.erl
@@ -5,7 +5,7 @@
 -include_lib("kernel/include/inet.hrl").
 -include_lib("hackney/include/hackney_lib.hrl").
 
--type url() :: binary() | nonempty_string().
+-type url() :: woody:url().
 -type parsed_url() :: #hackney_url{}.
 
 -type resolve_result() :: {Old::parsed_url(), New::parsed_url()}.
@@ -42,7 +42,7 @@ resolve_url(Url, WoodyState) ->
     {ok, resolve_result()}    |
     {error, Reason :: atom()}.
 resolve_url(Url, WoodyState, Opts) when is_list(Url) ->
-    resolve_url(list_to_binary(Url), WoodyState, Opts);
+    resolve_url(unicode:characters_to_binary(Url), WoodyState, Opts);
 resolve_url(<<"https://", _Rest/binary>> = Url, WoodyState, Opts) ->
     resolve_parsed_url(parse_url(Url), WoodyState, Opts);
 resolve_url(<<"http://", _Rest/binary>> = Url, WoodyState, Opts) ->