diff --git a/server/build_manifest.py b/server/build_manifest.py
index d5da5a6..b9f8065 100755
--- a/server/build_manifest.py
+++ b/server/build_manifest.py
@@ -10,6 +10,12 @@ import time
 
 
 parser = argparse.ArgumentParser(description='iconograph fetcher')
+parser.add_argument(
+    '--default-rollout',
+    dest='default_rollout',
+    action='store',
+    type=int,
+    default=0)
 parser.add_argument(
     '--image-dir',
     dest='image_dir',
@@ -64,7 +70,7 @@ class ManifestBuilder(object):
       timestamp = int(match.group('timestamp'))
       image = {
           'timestamp': timestamp,
-          'rollout_‱': rollouts.get(timestamp, 0),
+          'rollout_‱': rollouts.get(timestamp, FLAGS.default_rollout),
       }
       with open(os.path.join(self._image_dir, filename), 'rb') as fh:
         hash_obj = hashlib.sha256()