diff --git a/paramiko/dsskey.py b/paramiko/dsskey.py
index c26966e..6a46d32 100644
--- a/paramiko/dsskey.py
+++ b/paramiko/dsskey.py
@@ -111,9 +111,9 @@ class DSSKey (PKey):
         rstr = util.deflate_long(r, 0)
         sstr = util.deflate_long(s, 0)
         if len(rstr) < 20:
-            rstr += zero_byte * (20 - len(rstr))
+            rstr = zero_byte * (20 - len(rstr)) + rstr
         if len(sstr) < 20:
-            sstr += zero_byte * (20 - len(sstr))
+            sstr = zero_byte * (20 - len(sstr)) + sstr
         m.add_string(rstr + sstr)
         return m
 
diff --git a/sites/www/changelog.rst b/sites/www/changelog.rst
index 02fee80..6737fdc 100644
--- a/sites/www/changelog.rst
+++ b/sites/www/changelog.rst
@@ -2,6 +2,8 @@
 Changelog
 =========
 
+* :bug:`308` Fix regression in dsskey.py that caused sporadic signature 
+  verification failures. Thanks to Chris Rose.
 * :support:`290` (also :issue:`292`) Add support for building universal
   (Python 2+3 compatible) wheel files during the release process. Courtesy of
   Alex Gaynor.