diff --git a/doc/index.html b/doc/index.html
index 58d3e53..8467345 100755
--- a/doc/index.html
+++ b/doc/index.html
@@ -38,7 +38,7 @@ iterator requirements. The second is a framework of
 components for building iterators based on these
 extended concepts and includes several useful iterator
 adaptors. The extended iterator concepts have been
-carefully designed so that so that old-style iterators
+carefully designed so that old-style iterators
 can fit in the new concepts and so that new-style
 iterators will be compatible with old-style algorithms,
 though algorithms may need to be updated if they want to
diff --git a/doc/index.rst b/doc/index.rst
index 0d688c2..f181ab5 100755
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -29,7 +29,7 @@ __ ../../../index.htm
            components for building iterators based on these
            extended concepts and includes several useful iterator
            adaptors. The extended iterator concepts have been
-           carefully designed so that so that old-style iterators
+           carefully designed so that old-style iterators
            can fit in the new concepts and so that new-style
            iterators will be compatible with old-style algorithms,
            though algorithms may need to be updated if they want to