diff --git a/Doc/license.rst b/Doc/license.rst
index 41d1605..e1868e8 100644
--- a/Doc/license.rst
+++ b/Doc/license.rst
@@ -873,7 +873,7 @@
 ----
 
 The :mod:`zlib` extension is built using an included copy of the zlib
-sources unless the zlib version found on the system is too old to be
+sources if the zlib version found on the system is too old to be
 used for the build::
 
   Copyright (C) 1995-2011 Jean-loup Gailly and Mark Adler