diff --git a/tasks/update_phab.yml b/tasks/update_phab.yml
index 49a461d..508c859 100644
--- a/tasks/update_phab.yml
+++ b/tasks/update_phab.yml
@@ -1,74 +1,76 @@
 ---
 - name: Fix permission on phab git repo
   hosts: app, phd
   user: centos
   sudo: yes
   vars_files:
     - "{{ var }}"
   tasks:
     - shell: "chown -R {{ phd_user }}.{{ phd_user }} {{ phabricator_path }}"
 
 - name: Update phabricator on app instances
   hosts: app, phd
+  serial: 1
   user: centos
   sudo: yes
   sudo_user: "{{ phd_user }}"
   vars_files:
     - "{{ var }}"
   tasks:
     - name: Set git config
       shell: "git config --global user.email info@{{ domain }}; git config --global user.name ansible"
     - name: Stash modification
       shell: "cd {{ phabricator_path }}libphutil; git stash"
     - name: Clone phacility/libphutil
       git:
           repo: https://github.com/phacility/libphutil
           dest: "{{ phabricator_path }}libphutil"
           version: stable
           update: true
     - name: Stash apply modification
       shell: "cd {{ phabricator_path }}libphutil; git stash apply; true"
 
     - name: Stash modification
       shell: "cd {{ phabricator_path }}arcanist; git stash"
     - name: Clone phacility/arcanist
       git: 
           repo: https://github.com/phacility/arcanist.git
           dest: "{{ phabricator_path }}arcanist"
           version: stable
           update: true
     - name: Stash apply modification
       shell: "cd {{ phabricator_path }}arcanist; git stash apply; true"
 
     - name: Stash modification
       shell: "cd {{ phabricator_path }}phabricator; git stash"
     - name: Clone phacility/phabricator
       git:
           repo: https://github.com/phacility/phabricator.git
           dest: "{{ phabricator_path }}phabricator"
           version: stable
           update: true
     - name: Stash apply modification
       shell: "cd {{ phabricator_path }}phabricator; git stash apply; true"
 
     - name: Migrate the database
       command: chdir={{ phabricator_path }}phabricator ./bin/storage upgrade --force
       when: "'{{ inventory_hostname }}' == '{{ groups.app[0] }}'"
 
 - name: Restart httpd daemons
   hosts: app
+  serial: 1
   user: centos
   sudo: yes
   vars_files:
     - "{{ var }}"
   tasks:
     - service: name=httpd state=restarted
 
 - name: Restart phd daemons
   hosts: phd
   user: centos
   sudo: yes
   vars_files:
     - "{{ var }}"
   tasks:
     - service: name=phd state=restarted