diff --git a/zipline/transforms/stddev.py b/zipline/transforms/stddev.py
index bcb9fb38..f237ef1f 100644
--- a/zipline/transforms/stddev.py
+++ b/zipline/transforms/stddev.py
@@ -22,7 +22,7 @@ from zipline.transforms.utils import EventWindow, TransformMeta
 
 class MovingStandardDev(object):
     """
-    Class that maintains a dicitonary from sids to
+    Class that maintains a dictionary from sids to
     MovingStandardDevWindows.  For each sid, we maintain a the
     standard deviation of all events falling within the specified
     window.