diff --git a/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter.rb b/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter.rb
index a027e6a17..316a7b8fd 100644
--- a/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter.rb
+++ b/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter.rb
@@ -38,8 +38,8 @@ module Redmine
               node.inner_html = html
               node["class"] = "#{lang} syntaxhl"
             else
-              # unsupported language, strip out the code tag
-              node.parent.inner_html = text
+              # unsupported language, remove the class attribute
+              node.remove_attribute("class")
             end
           end
           doc