diff --git a/bitbake/lib/prserv/__init__.py b/bitbake/lib/prserv/__init__.py
index a817b03c1e..ffc5a40a28 100644
--- a/bitbake/lib/prserv/__init__.py
+++ b/bitbake/lib/prserv/__init__.py
@@ -34,7 +34,7 @@ def increase_revision(ver):
          logger.critical("Unable to increase revision value %s: %s" % (ver, e))
          raise e
 
-    return ".".join(fields[0:-1] + list(str(val + 1)))
+    return ".".join(fields[0:-1] + [ str(val + 1) ])
 
 def _revision_greater_or_equal(rev1, rev2):
     """Compares x.y.z revision numbers, using integer comparison
diff --git a/bitbake/lib/prserv/tests.py b/bitbake/lib/prserv/tests.py
index 8765b129f2..df0c003003 100644
--- a/bitbake/lib/prserv/tests.py
+++ b/bitbake/lib/prserv/tests.py
@@ -84,6 +84,8 @@ class FunctionTests(unittest.TestCase):
         self.assertEqual(increase_revision("1.0"), "1.1")
         self.assertEqual(increase_revision("1.1.1"), "1.1.2")
         self.assertEqual(increase_revision("1.1.1.3"), "1.1.1.4")
+        self.assertEqual(increase_revision("9"), "10")
+        self.assertEqual(increase_revision("1.9"), "1.10")
         self.assertRaises(ValueError, increase_revision, "1.a")
         self.assertRaises(ValueError, increase_revision, "1.")
         self.assertRaises(ValueError, increase_revision, "")