diff --git a/lib/middleman-syntax/haml_monkey_patch.rb b/lib/middleman-syntax/haml_monkey_patch.rb
index 91e9497..5e0bea8 100644
--- a/lib/middleman-syntax/haml_monkey_patch.rb
+++ b/lib/middleman-syntax/haml_monkey_patch.rb
@@ -1,22 +1,36 @@
 # If Haml is around, define a :code filter that can be used to more conveniently output highlighted code.
+
 if defined? Haml
-  module Haml
-    module Filters
-      module Code
-        include Base
+  module HamlMonkeyPatch
+    def render(code)
+      code = code.rstrip
+      code = code.encode(Encoding::UTF_8)
 
-        def render(code)
-          code = code.rstrip
-          code = code.encode(Encoding::UTF_8)
+      # Allow language to be specified via a special comment like:
+      # # lang: ruby
+      if code.lines.first =~ /\A\s*#\s*lang:\s*(\w+)$/
+        language = $1
+        code = code.lines.to_a[1..-1].join # Strip first line
+      end
 
-          # Allow language to be specified via a special comment like:
-          #  # lang: ruby
-          if code.lines.first =~ /\A\s*#\s*lang:\s*(\w+)$/
-              language = $1
-            code = code.lines.to_a[1..-1].join # Strip first line
-          end
+      Middleman::Syntax::Highlighter.highlight(code, language)
+    end
+  end
 
-          Middleman::Syntax::Highlighter.highlight(code, language)
+  if Gem::Version.new(Haml::VERSION) >= Gem::Version.new("6.0.0")
+    module Haml
+      class Filters
+        class Code < Base
+          extend HamlMonkeyPatch
+        end
+      end
+    end
+  else
+    module Haml
+      module Filters
+        module Code
+          include Base
+          extend HamlMonkeyPatch
         end
       end
     end