diff --git a/users.py b/users.py
index 0cc7ca2..a22a247 100644
--- a/users.py
+++ b/users.py
@@ -42,13 +42,14 @@
     return None
 
 def set_session_user(username):
+    r.sadd("apex:users", username)
     flask.session["username"] = username
 
 def user_is_admin(username=None):
     if username is None:
         username = session_user()
-    if username is None:
-        return False
+        if username is None:
+            return False
     return bool(r.get("apex:users:{}:admin".format(username)))
 
 def user_set_admin(username):