diff --git a/jupyterhub/apihandlers/users.py b/jupyterhub/apihandlers/users.py
index e6066513..6ff84529 100644
--- a/jupyterhub/apihandlers/users.py
+++ b/jupyterhub/apihandlers/users.py
@@ -68,6 +68,7 @@ class UserAPIHandler(BaseUserHandler):
         self.write(json.dumps(self.user_model(user)))
     
     @admin_only
+    @gen.coroutine
     def post(self, name):
         data = self.get_json_body()
         user = self.find_user(name)
@@ -82,7 +83,7 @@ class UserAPIHandler(BaseUserHandler):
                 self.db.commit()
         
         try:
-            self.authenticator.add_user(user)
+            yield gen.maybe_future(self.authenticator.add_user(user))
         except Exception:
             self.log.error("Failed to create user: %s" % name, exc_info=True)
             self.db.delete(user)
@@ -103,7 +104,7 @@ class UserAPIHandler(BaseUserHandler):
         if user.spawner is not None:
             yield self.stop_single_user(user)
         
-        self.authenticator.delete_user(user)
+        yield gen.maybe_future(self.authenticator.delete_user(user))
         
         # remove from the db
         self.db.delete(user)
diff --git a/jupyterhub/auth.py b/jupyterhub/auth.py
index 5461e8b0..c8b0fd58 100644
--- a/jupyterhub/auth.py
+++ b/jupyterhub/auth.py
@@ -84,6 +84,7 @@ class LocalAuthenticator(Authenticator):
         """
     )
     
+    @gen.coroutine
     def add_user(self, user):
         """Add a new user
         
@@ -92,13 +93,14 @@ class LocalAuthenticator(Authenticator):
         Subclasses may do more extensive things,
         such as adding actual unix users.
         """
-        if not self.system_user_exists(user):
+        user_exists = yield gen.maybe_future(self.system_user_exists(user))
+        if not user_exists:
             if self.create_system_users:
-                self.add_system_user(user)
+                yield gen.maybe_future(self.add_system_user(user))
             else:
                 raise KeyError("User %s does not exist." % user.name)
         
-        super(LocalAuthenticator, self).add_user(user)
+        yield gen.maybe_future(super().add_user(user))
     
     @staticmethod
     def system_user_exists(user):