diff --git a/schema/0101_acting_usr.sql b/schema/0101_acting_usr.sql
index a448105..bdb9f9e 100644
--- a/schema/0101_acting_usr.sql
+++ b/schema/0101_acting_usr.sql
@@ -4,7 +4,19 @@ create function public.set_acting_usr(uid text)
   volatile
   as $$
 begin
-  set session "dnim.usr_uid" = uid;
+  if uid is not null and uid != '' then
+    perform set_config('dnim.usr_uid', uid, false);
+  end if;
+end;
+$$;
+
+create function public.unset_acting_usr()
+  returns void
+  language plpgsql
+  volatile
+  as $$
+begin
+  perform set_config('dnim.usr_uid', '', false);
 end;
 $$;
 
@@ -14,18 +26,17 @@ create function public.get_acting_usr()
   volatile
 as $$
 declare
-  uid text;
   acting_usr public.usr;
 begin
   if nullif(current_setting('dnim.usr_uid', true), '') is null then
     acting_usr := public.usr_root();
-  else 
+  else
     select u.*
     from public.usr u
     where u.uid = human_uuid.huid_of_string(current_setting('dnim.usr_uid', true))
     into acting_usr;
   end if;
 
-  return acting_usr;
+  return coalesce(acting_usr, public.usr_root());
 end;
 $$;