diff --git a/jupyterhub/singleuserapp.py b/jupyterhub/singleuserapp.py
index 81957127..6085c805 100644
--- a/jupyterhub/singleuserapp.py
+++ b/jupyterhub/singleuserapp.py
@@ -99,8 +99,8 @@ class SingleUserNotebookApp(NotebookApp):
         s = self.webapp_settings
         s['token_cache'] = {}
         s['user'] = self.user
-        s['hub_api_key'] = env.get('IPY_API_TOKEN', '')
-        s['cookie_secret'] = env.get('IPY_COOKIE_SECRET', '')
+        s['hub_api_key'] = env.pop('JPY_API_TOKEN', '')
+        s['cookie_secret'] = env.pop('JPY_COOKIE_SECRET', '')
         s['cookie_name'] = self.cookie_name
         s['login_url'] = url_path_join(self.hub_prefix, 'login')
         s['hub_api_url'] = self.hub_api_url
diff --git a/jupyterhub/spawner.py b/jupyterhub/spawner.py
index 4888cfb0..1fa93025 100644
--- a/jupyterhub/spawner.py
+++ b/jupyterhub/spawner.py
@@ -39,7 +39,7 @@ class Spawner(LoggingConfigurable):
     hub = Any()
     api_token = Unicode()
     
-    env_prefix = Unicode('IPY_')
+    env_prefix = Unicode('JPY_')
     def _env_key(self, d, key, value):
         d['%s%s' % (self.env_prefix, key)] = value