diff --git a/.sync.yml b/.sync.yml
index 8974464..8158496 100644
--- a/.sync.yml
+++ b/.sync.yml
@@ -12,4 +12,6 @@ Gemfile:
     ':development':
       - gem: 'puppet-blacksmith'
       - gem: 'github_changelog_generator'
-
+      - gem: 'rexml'
+        version: '~> 3.2'
+        condition: "Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3')"
diff --git a/Gemfile b/Gemfile
index 5b241e2..4a398ec 100644
--- a/Gemfile
+++ b/Gemfile
@@ -37,6 +37,7 @@ group :development do
   gem "rb-readline", '= 0.5.5',                  require: false, platforms: [:mswin, :mingw, :x64_mingw]
   gem "puppet-blacksmith",                       require: false
   gem "github_changelog_generator",              require: false
+  gem "rexml", '~> 3.2',                         require: false if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3')
 end
 group :system_tests do
   gem "puppet_litmus", '~> 1.0', require: false, platforms: [:ruby, :x64_mingw]
diff --git a/README.md b/README.md
index d4a5c19..daccaf6 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,13 @@
 5. [Contributing](#contributing)
 
 ## Upgrade warnings:
+
+Upgrading to puppet 8 comes with Ruby 3, which doesn't have the `rexml` gem bundled.
+It should be [installed on the puppetserver](https://www.puppet.com/docs/puppet/7/server/gems.html#installing-and-removing-gems).
+```
+sudo puppetserver gem install rexml
+```
+
 Upgrade to version 5.x.x introduced types/providers for network, nwfilter and domains 
 replacing the execs used before version 5.0.0. To compare the XML's generated with puppet and
 the actual running XML's generated with virsh they are sorted which leads to display lots of