diff --git a/subcmds/sync.py b/subcmds/sync.py
index 80bba1a..36ef16d 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -185,6 +185,8 @@
         t.join()
 
     pm.end()
+    for project in projects:
+      project.bare_git.gc('--auto')
     return fetched
 
   def UpdateProjectList(self):