diff --git a/pandas/core/groupby.py b/pandas/core/groupby.py
index 705e1574efe06..3399e1fb30bde 100644
--- a/pandas/core/groupby.py
+++ b/pandas/core/groupby.py
@@ -25,7 +25,7 @@
 arg : function or dict
     Function to use for aggregating groups. If a function, must either
     work when passed a DataFrame or when passed to DataFrame.apply. If
-    pass a dict, the keys must be DataFrame column names
+    passed a dict, the keys must be DataFrame column names.
 
 Notes
 -----