diff --git a/lib/nokogiri/xml/node.rb b/lib/nokogiri/xml/node.rb
index 2e701a4d4f7..1780c6ceca7 100644
--- a/lib/nokogiri/xml/node.rb
+++ b/lib/nokogiri/xml/node.rb
@@ -847,9 +847,12 @@ def add_sibling next_or_previous, node_or_tags
         node_or_tags
       end
 
+      IS_BROKEN_LIBXML_VERSION = defined?(LIBXML_VERSION) && LIBXML_VERSION.start_with?('2.6').freeze
+      private_constant :IS_BROKEN_LIBXML_VERSION
+
       def to_format save_option, options
         # FIXME: this is a hack around broken libxml versions
-        return dump_html if Nokogiri.uses_libxml? && %w[2 6] === LIBXML_VERSION.split('.')[0..1]
+        return dump_html if Nokogiri.uses_libxml? && IS_BROKEN_LIBXML_VERSION
 
         options[:save_with] = save_option unless options[:save_with]
         serialize(options)
@@ -857,7 +860,7 @@ def to_format save_option, options
 
       def write_format_to save_option, io, options
         # FIXME: this is a hack around broken libxml versions
-        return (io << dump_html) if Nokogiri.uses_libxml? && %w[2 6] === LIBXML_VERSION.split('.')[0..1]
+        return (io << dump_html) if Nokogiri.uses_libxml? && IS_BROKEN_LIBXML_VERSION
 
         options[:save_with] ||= save_option
         write_to io, options