diff --git a/base.yml b/base.yml
index 5bf6a4e7dc88b91a4fbc0e7ffb685ea53c6d0519..1f3d65060cec3684cb282dacad4e1dfa9d6cc35e 100755
--- a/base.yml
+++ b/base.yml
@@ -6,8 +6,8 @@
     - name: Register adm interface in adm_iface variable
       shell: set -o pipefail && grep adm /sys/class/net/*/ifalias | sed "s|/sys/class/net/||" | sed "s|/ifalias:.*||"
       register: adm_iface
-      check_mode: no
-      changed_when: True
+      check_mode: false
+      changed_when: true
       args:
         executable: /bin/bash
 
diff --git a/interfaces.yml b/interfaces.yml
index 5c7107a7709108dcd65a2333ebb473abc6883991..bce7ced2325c8ed164126072e3ffb393c35c4b0d 100755
--- a/interfaces.yml
+++ b/interfaces.yml
@@ -4,7 +4,7 @@
 - hosts: server
   tasks:
     - shell: "grep {{ item }} /sys/class/net/*/ifalias | sed \"s|/sys/class/net/||\" | sed \"s|/ifalias:.*||\""
-      check_mode: no
+      check_mode: false
       register: ifaces
       loop:
         - srv
diff --git a/network.yml b/network.yml
index daf70236ed79cc054bbc724834f6cff0277cdc66..fdc49662d711d8a0eff538e318f24d603dccf2e1 100755
--- a/network.yml
+++ b/network.yml
@@ -65,7 +65,7 @@
         cert: /etc/letsencrypt/live/crans.org/fullchain.pem
         cert_key: /etc/letsencrypt/live/crans.org/privkey.pem
         trusted_cert: /etc/letsencrypt/live/crans.org/chain.pem
- 
+
       redirect_dnames:
         - crans.eu
         - crans.fr
diff --git a/roles/postfix/handlers/main.yml b/roles/postfix/handlers/main.yml
index 4909464976c676d12f8bbdc4dc69208458e48eba..8fa449d505055a7709a5a6f88635acf8de3faee7 100644
--- a/roles/postfix/handlers/main.yml
+++ b/roles/postfix/handlers/main.yml
@@ -1,3 +1,4 @@
+---
 - name: generate postmaps
   command: /usr/sbin/postmap {{ item }}
   loop:
diff --git a/upgrade.yml b/upgrade.yml
index 27798c1586d464ba55a70fd8162a880b65285caa..194f0137d9c232f90f15f94e12083cebbe72e19a 100755
--- a/upgrade.yml
+++ b/upgrade.yml
@@ -21,7 +21,7 @@
 
 - hosts: owncloud-srv.adm.crans.org
   become_user: www-data
-  become: yes
+  become: true
   vars:
     # Owncloud command line interface
     occ_bin: '/var/www/owncloud/occ'