diff --git a/config/initializers/haml.rb b/config/initializers/haml.rb
index 1d43f2c82f..47ef4ea26e 100644
--- a/config/initializers/haml.rb
+++ b/config/initializers/haml.rb
@@ -1,2 +1,5 @@
 require 'haml'
-Haml::Template.options[:ugly] = true
+
+if Gem::Version.create(Haml::VERSION) < Gem::Version.create('5.0.0.beta.2')
+  Haml::Template.options[:ugly] = true
+end
diff --git a/rails_admin.gemspec b/rails_admin.gemspec
index 2e70993522..22f2fc82d1 100644
--- a/rails_admin.gemspec
+++ b/rails_admin.gemspec
@@ -8,7 +8,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'builder', '~> 3.1'
   spec.add_dependency 'coffee-rails', '~> 4.0'
   spec.add_dependency 'font-awesome-rails', ['>= 3.0', '< 5']
-  spec.add_dependency 'haml', '~> 4.0'
+  spec.add_dependency 'haml', '>= 4.0', '< 6'
   spec.add_dependency 'jquery-rails', ['>= 3.0', '< 5']
   spec.add_dependency 'jquery-ui-rails', '~> 5.0'
   spec.add_dependency 'kaminari', '>= 0.14', '< 2.0'