diff --git a/horizon/version.py b/horizon/version.py
index <HASH>..<HASH> 100644
--- a/horizon/version.py
+++ b/horizon/version.py
@@ -19,13 +19,13 @@ version_info = {'branch_nick': u'LOCALBRANCH',
                 'revno': 0}
 
 
-HORIZON_VERSION = ['2012', '2']
-YEAR, COUNT = HORIZON_VERSION
+HORIZON_VERSION = ['2012', '2', None]
+YEAR, COUNT, REVISION = HORIZON_VERSION
 FINAL = False   # This becomes true at Release Candidate time
 
 
 def canonical_version_string():
-    return '.'.join([YEAR, COUNT])
+    return '.'.join(filter(None, HORIZON_VERSION))
 
 
 def version_string():
Support revisions in version numbers

Introduce REVISION in versioning scheme, in order to support future
stable versioning (<I>.x).

Change-Id: I<I>cfbf<I>c<I>bbda8d<I>fdbd<I>b<I>a6b