nuke trailing whitespace
diff --git a/docs/x509/reference.rst b/docs/x509/reference.rst
index 15078e9..72603f4 100644
--- a/docs/x509/reference.rst
+++ b/docs/x509/reference.rst
@@ -520,7 +520,7 @@
             Must support the
             :class:`~cryptography.hazmat.backends.interfaces.X509Backend`
             interface.
-            
+
         :returns: :class:`~cryptography.x509.Certificate`