diff --git a/manifests/module/incubator.pp b/manifests/module/incubator.pp
index 2ecab28..130afe6 100644
--- a/manifests/module/incubator.pp
+++ b/manifests/module/incubator.pp
@@ -1,28 +1,28 @@
 # == Class: icingaweb2::module::incubator
 #
 # Install and enable the incubator module.
 #
 # === Parameters
 #
 # [*ensure*]
 #   Enable or disable module. Defaults to `present`
 #
 # [*git_repository*]
 #   Set a git repository URL. Defaults to github.
 #
 # [*git_revision*]
 #   Set either a branch or a tag name, eg. `stable/0.7.0` or `v0.7.0`.
 #
 class icingaweb2::module::incubator(
+  String                    $git_revision,
   Enum['absent', 'present'] $ensure         = 'present',
   String                    $git_repository = 'https://github.com/Icinga/icingaweb2-module-incubator.git',
-  String                    $git_revision   = undef,
 ){
 
   icingaweb2::module { 'incubator':
     ensure         => $ensure,
     git_repository => $git_repository,
     git_revision   => $git_revision,
   }
 
 }
diff --git a/manifests/module/ipl.pp b/manifests/module/ipl.pp
index eeb6b76..2b91321 100644
--- a/manifests/module/ipl.pp
+++ b/manifests/module/ipl.pp
@@ -1,28 +1,28 @@
 # == Class: icingaweb2::module::ipl
 #
 # Install and enable the ipl module.
 #
 # === Parameters
 #
 # [*ensure*]
 #   Enable or disable module. Defaults to `present`
 #
 # [*git_repository*]
 #   Set a git repository URL. Defaults to github.
 #
 # [*git_revision*]
 #   Set either a branch or a tag name, eg. `stable/0.7.0` or `v0.7.0`.
 #
 class icingaweb2::module::ipl(
+  String                    $git_revision,
   Enum['absent', 'present'] $ensure         = 'present',
   String                    $git_repository = 'https://github.com/Icinga/icingaweb2-module-ipl.git',
-  String                    $git_revision   = undef,
 ){
 
   icingaweb2::module { 'ipl':
     ensure         => $ensure,
     git_repository => $git_repository,
     git_revision   => $git_revision,
   }
 
 }
diff --git a/manifests/module/reactbundle.pp b/manifests/module/reactbundle.pp
index f446330..cd050c9 100644
--- a/manifests/module/reactbundle.pp
+++ b/manifests/module/reactbundle.pp
@@ -1,29 +1,29 @@
 # == Class: icingaweb2::module::reactbundle
 #
 # Install and enable the reactbundle module.
 #
 # === Parameters
 #
 # [*ensure*]
 #   Enable or disable module. Defaults to `present`
 #
 # [*git_repository*]
 #   Set a git repository URL. Defaults to github.
 #
 # [*git_revision*]
 #   Set either a branch or a tag name, eg. `stable/0.7.0` or `v0.7.0`.
 #
 class icingaweb2::module::reactbundle(
+  String                    $git_revision,
   Enum['absent', 'present'] $ensure         = 'present',
   String                    $git_repository = 'https://github.com/Icinga/icingaweb2-module-reactbundle.git',
-  String                    $git_revision   = undef,
 ){
 
   icingaweb2::module { 'reactbundle':
     ensure         => $ensure,
     git_repository => $git_repository,
     git_revision   => $git_revision,
   }
 
 }
 
diff --git a/manifests/repo.pp b/manifests/repo.pp
index b8bebe8..8fe5966 100644
--- a/manifests/repo.pp
+++ b/manifests/repo.pp
@@ -1,104 +1,104 @@
 # == Class: icingaweb2::repo
 #
 # This class manages the packages.icinga.com repository based on the operating system.
 #
 # === Parameters
 #
 # This class does not provide any parameters.
 # To control the behaviour of this class, have a look at the parameters:
 # * icingaweb2::manage_repo
 #
 # === Examples
 #
 # This class is private and should not be called by others than this module.
 #
 class icingaweb2::repo {
 
   assert_private("You're not supposed to use this defined type manually.")
 
   if $::icingaweb2::manage_repo and $::icingaweb2::manage_package {
 
     case $::facts['os']['family'] {
       'redhat': {
         case $::facts['os']['name'] {
           'centos', 'redhat': {
             yumrepo { 'icinga-stable-release':
               baseurl  => "http://packages.icinga.com/epel/${::facts['os']['release']['major']}/release/",
               descr    => 'ICINGA (stable release for epel)',
               enabled  => 1,
               gpgcheck => 1,
               gpgkey   => 'http://packages.icinga.com/icinga.key',
             }
           }
           default: {
             fail('Your plattform is not supported to manage a repository.')
           }
         }
       }
       'debian': {
         case $::facts['os']['name'] {
           'debian': {
             include ::apt, ::apt::backports
             apt::source { 'icinga-stable-release':
               location => 'http://packages.icinga.com/debian',
               release  => "icinga-${::facts['lsbdistcodename']}",
               repos    => 'main',
               key      => {
                 id     => 'F51A91A5EE001AA5D77D53C4C6E319C334410682',
                 source => 'http://packages.icinga.com/icinga.key',
               };
             }
           }
           'ubuntu': {
             include ::apt
             apt::source { 'icinga-stable-release':
               location => 'http://packages.icinga.com/ubuntu',
               release  => "icinga-${::facts['lsbdistcodename']}",
               repos    => 'main',
               key      => {
                 id     => 'F51A91A5EE001AA5D77D53C4C6E319C334410682',
                 source => 'http://packages.icinga.com/icinga.key',
               };
             }
           }
           default: {
             fail('Your plattform is not supported to manage a repository.')
           }
         }
         contain ::apt::update
       }
       'suse': {
 
         file { '/etc/pki/GPG-KEY-icinga':
           ensure => present,
           source => 'http://packages.icinga.com/icinga.key',
         }
 
         exec { 'import icinga gpg key':
           path      => '/bin:/usr/bin:/sbin:/usr/sbin',
           command   => 'rpm --import /etc/pki/GPG-KEY-icinga',
-          unless    => "rpm -q gpg-pubkey-`echo $(gpg --throw-keyids < /etc/pki/GPG-KEY-icinga) | cut --characters=11-18 | tr [A-Z] [a-z]`",
+          unless    => 'rpm -q gpg-pubkey-`echo $(gpg --throw-keyids < /etc/pki/GPG-KEY-icinga) | cut --characters=11-18 | tr [A-Z] [a-z]',
           require   => File['/etc/pki/GPG-KEY-icinga'],
           logoutput => 'on_failure',
         }
 
         case $::facts['os']['name'] {
           'SLES': {
             zypprepo { 'icinga-stable-release':
               baseurl  => "http://packages.icinga.com/SUSE/${::facts['os']['release']['full']}/release/",
               enabled  => 1,
               gpgcheck => 1,
               require  => Exec['import icinga gpg key']
             }
           }
           default: {
             fail('Your plattform is not supported to manage a repository.')
           }
         }
       }
       default: {
         fail('Your plattform is not supported to manage a repository.')
       }
     }
   } # if $::icinga::manage_repo
 }