diff --git a/jupyterhub/spawner.py b/jupyterhub/spawner.py
index 1436dea6..57f0a50a 100644
--- a/jupyterhub/spawner.py
+++ b/jupyterhub/spawner.py
@@ -516,11 +516,14 @@ class Spawner(LoggingConfigurable):
 
     pre_spawn_hook = Any(
         help="""
-        An optional hook function that you can implement to do some bootstrapping work before
-        the spawner starts. For example, create a directory for your user or load initial content.
+        An optional hook function that you can implement to do some
+        bootstrapping work before the spawner starts. For example, create a
+        directory for your user or load initial content.
 
         This can be set independent of any concrete spawner implementation.
 
+        This maybe a coroutine.
+
         Example::
 
             from subprocess import check_call