Remove trailing whitespace.
diff --git a/Doc/c-api/set.rst b/Doc/c-api/set.rst
index c6b097d..a60ccd6 100644
--- a/Doc/c-api/set.rst
+++ b/Doc/c-api/set.rst
@@ -101,7 +101,7 @@
 
    .. versionchanged:: 2.6
       Now guaranteed to return a brand-new :class:`frozenset`.  Formerly,
-      frozensets of zero-length were a singleton.  This got in the way of 
+      frozensets of zero-length were a singleton.  This got in the way of
       building-up new frozensets with :meth:`PySet_Add`.
 
 The following functions and macros are available for instances of :class:`set`