diff --git a/modules/openstack_project/manifests/puppetmaster.pp b/modules/openstack_project/manifests/puppetmaster.pp
index 9d9c46456e..5ed3aad3bf 100644
--- a/modules/openstack_project/manifests/puppetmaster.pp
+++ b/modules/openstack_project/manifests/puppetmaster.pp
@@ -51,7 +51,7 @@ class openstack_project::puppetmaster (
   cron { 'updatepuppetmaster':
     user        => 'root',
     minute      => '*/15',
-    command     => 'bash /opt/system-config/production/run_all.sh',
+    command     => 'flock -n /var/run/puppet/puppet_run_all.lock bash /opt/system-config/production/run_all.sh',
     environment => 'PATH=/var/lib/gems/1.8/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin',
   }