Single space.
diff --git a/docs/hazmat/primitives/interfaces.rst b/docs/hazmat/primitives/interfaces.rst
index b526158..f37dbb5 100644
--- a/docs/hazmat/primitives/interfaces.rst
+++ b/docs/hazmat/primitives/interfaces.rst
@@ -5,8 +5,8 @@
``cryptography`` uses `Abstract Base Classes`_ as interfaces to describe the
-properties and methods of most primitive constructs. Backends may also use
-this information to influence their operation. Interfaces should also be used
+properties and methods of most primitive constructs. Backends may also use
+this information to influence their operation. Interfaces should also be used
to document argument and return types.
.. _`Abstract Base Classes`: http://www.python.org/dev/peps/pep-3119/