diff --git a/notebook/notebookapp.py b/notebook/notebookapp.py
index 9a5f3d122..aee89cfcb 100644
--- a/notebook/notebookapp.py
+++ b/notebook/notebookapp.py
@@ -528,7 +528,7 @@ class NotebookApp(JupyterApp):
     )
     
     client_ca = Unicode(u'', config=True,
-        help="""The full path to a certificate authority certifificate for SSL/TLS client authentication."""
+        help="""The full path to a certificate authority certificate for SSL/TLS client authentication."""
     )
     
     cookie_secret_file = Unicode(config=True,