diff --git a/lib/redmine/wiki_formatting/common_mark/sanitization_filter.rb b/lib/redmine/wiki_formatting/common_mark/sanitization_filter.rb
index 94e4b8f5e..69805491a 100644
--- a/lib/redmine/wiki_formatting/common_mark/sanitization_filter.rb
+++ b/lib/redmine/wiki_formatting/common_mark/sanitization_filter.rb
@@ -48,7 +48,7 @@ module Redmine
             return unless node.name == "code"
             return unless node.has_attribute?("class")
 
-            unless /\Alanguage-(\w+)\z/.match?(node["class"])
+            unless /\Alanguage-(\S+)\z/.match?(node["class"])
               node.remove_attribute("class")
             end
           }
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 316a7b8fd..f561488e5 100644
--- a/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter.rb
+++ b/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter.rb
@@ -26,11 +26,14 @@ module Redmine
         def call
           doc.search("pre > code").each do |node|
             next unless lang = node["class"].presence
-            next unless lang =~ /\Alanguage-(\w+)\z/
+            next unless lang =~ /\Alanguage-(\S+)\z/
 
             lang = $1
             text = node.inner_text
 
+            # original language for extension development
+            node["data-language"] = lang unless node["data-language"]
+
             if Redmine::SyntaxHighlighting.language_supported?(lang)
               html = Redmine::SyntaxHighlighting.highlight_by_language(text, lang)
               next if html.nil?
diff --git a/test/unit/lib/redmine/wiki_formatting/common_mark/formatter_test.rb b/test/unit/lib/redmine/wiki_formatting/common_mark/formatter_test.rb
index d121d5425..cd5e89931 100644
--- a/test/unit/lib/redmine/wiki_formatting/common_mark/formatter_test.rb
+++ b/test/unit/lib/redmine/wiki_formatting/common_mark/formatter_test.rb
@@ -94,24 +94,31 @@ class Redmine::WikiFormatting::CommonMark::FormatterTest < ActionView::TestCase
     end
 
     def test_should_support_syntax_highlight
-      text = <<-STR
-  ~~~ruby
-  def foo
-  end
-  ~~~
+      text = <<~STR
+        ~~~ruby
+        def foo
+        end
+        ~~~
       STR
       assert_select_in format(text), 'pre code.ruby.syntaxhl' do
         assert_select 'span.k', :text => 'def'
+        assert_select "[data-language='ruby']"
       end
     end
 
-    def test_should_not_allow_invalid_language_for_code_blocks
-      text = <<-STR
-  ~~~foo
-  test
-  ~~~
+    def test_should_support_syntax_highlight_for_language_with_special_chars
+      text = <<~STR
+        ~~~c++
+        int main() {
+        }
+        ~~~
       STR
-      assert_equal "<pre>test\n</pre>", format(text)
+
+      assert_select_in format(text), 'pre' do
+        assert_select 'code[class=?]', "c++ syntaxhl"
+        assert_select 'span.kt', :text => 'int'
+        assert_select "[data-language=?]", "c++"
+      end
     end
 
     def test_external_links_should_have_external_css_class
diff --git a/test/unit/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter_test.rb b/test/unit/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter_test.rb
index e7e782d53..586dbbe1e 100644
--- a/test/unit/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter_test.rb
+++ b/test/unit/lib/redmine/wiki_formatting/common_mark/syntax_highlight_filter_test.rb
@@ -38,7 +38,7 @@ if Object.const_defined?(:CommonMarker)
         </code></pre>
       HTML
       expected = <<~HTML
-        <pre><code class="ruby syntaxhl">
+        <pre><code class="ruby syntaxhl" data-language="ruby">
         <span class="k">def</span> <span class="nf">foo</span>
         <span class="k">end</span>
         </code></pre>
@@ -46,7 +46,21 @@ if Object.const_defined?(:CommonMarker)
       assert_equal expected, filter(input)
     end
 
-    def test_should_strip_code_for_unknown_lang
+    def test_should_highlight_supported_language_with_special_chars
+      input = <<~HTML
+        <pre><code class="language-c-k&amp;r">
+        int i;
+        </code></pre>
+      HTML
+      expected = <<~HTML
+        <pre><code data-language="c-k&amp;r">
+        int i;
+        </code></pre>
+      HTML
+      assert_equal expected, filter(input)
+    end
+
+    def test_should_strip_code_class_and_preserve_data_language_attr_for_unknown_language
       input = <<~HTML
         <pre><code class="language-foobar">
         def foo
@@ -54,10 +68,10 @@ if Object.const_defined?(:CommonMarker)
         </code></pre>
       HTML
       expected = <<~HTML
-        <pre>
+        <pre><code data-language="foobar">
         def foo
         end
-        </pre>
+        </code></pre>
       HTML
       assert_equal expected, filter(input)
     end