Fix typo
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index df231f8..14ccffb 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -72,7 +72,7 @@
 
       A user updateable list of mappings.  The list is ordered from
       first-searched to last-searched.  It is the only stored state and can
-      modified to change which mappings are searched.  The list should
+      be modified to change which mappings are searched.  The list should
       always contain at least one mapping.
 
    .. method:: new_child()