diff --git a/zomp/lib/otpr-zx/0.1.0/src/zx.erl b/zomp/lib/otpr-zx/0.1.0/src/zx.erl
index f98d445..7f93cbb 100644
--- a/zomp/lib/otpr-zx/0.1.0/src/zx.erl
+++ b/zomp/lib/otpr-zx/0.1.0/src/zx.erl
@@ -52,8 +52,8 @@
 -type key_id()          :: {realm(), key_name()}.
 -type key_name()        :: lower0_9().
 -type key_data()        :: {ID      :: key_id(),
-                            Public  :: binary() | none,
-                            Private :: binary() | none}.
+                            Public  :: binary() | <<>>,
+                            Private :: binary() | <<>>}.
 -type user_id()         :: {realm(), user_name()}.
 -type user_name()       :: label().
 -type contact_info()    :: {Type :: string(), Data :: string()}.