diff --git a/lib/redmine/wiki_formatting/textile/formatter.rb b/lib/redmine/wiki_formatting/textile/formatter.rb
index 63851a21a5..6e7f28e621 100644
--- a/lib/redmine/wiki_formatting/textile/formatter.rb
+++ b/lib/redmine/wiki_formatting/textile/formatter.rb
@@ -120,7 +120,7 @@ module Redmine
             ## replace <pre> content
             text.gsub!(/<redpre#(\d+)>/) do
               content = @pre_list[$1.to_i]
-              if content.match(/<code\s+class="(\w+)">\s?(.+)/m)
+              if content.match(/<code\s+class=["'](\w+)["']>\s?(.+)/m)
                 language = $1
                 text = $2
                 if Redmine::SyntaxHighlighting.language_supported?(language)
diff --git a/test/unit/lib/redmine/wiki_formatting/textile_formatter_test.rb b/test/unit/lib/redmine/wiki_formatting/textile_formatter_test.rb
index 059f0b83a0..712bc5000f 100644
--- a/test/unit/lib/redmine/wiki_formatting/textile_formatter_test.rb
+++ b/test/unit/lib/redmine/wiki_formatting/textile_formatter_test.rb
@@ -546,7 +546,10 @@ STR
   end
 
   def test_should_allow_valid_language_class_attribute_on_code_tags
+    # language name is double-quoted
     assert_html_output({"<code class=\"ruby\">test</code>" => "<code class=\"ruby syntaxhl\"><span class=\"CodeRay\">test</span></code>"}, false)
+    # language name is single-quoted
+    assert_html_output({"<code class='ruby'>test</code>" => "<code class=\"ruby syntaxhl\"><span class=\"CodeRay\">test</span></code>"}, false)
   end
 
   def test_should_not_allow_valid_language_class_attribute_on_non_code_offtags