diff --git a/spec/std/markdown/markdown_spec.cr b/spec/std/markdown/markdown_spec.cr
index 557292b21792..30a3bda227ef 100644
--- a/spec/std/markdown/markdown_spec.cr
+++ b/spec/std/markdown/markdown_spec.cr
@@ -67,7 +67,7 @@ describe Markdown do
   assert_render "    Hello\n   World", "<pre><code>Hello</code></pre>\n\n<p>World</p>"
   assert_render "    Hello\n\n\nWorld", "<pre><code>Hello</code></pre>\n\n<p>World</p>"
 
-  assert_render "```crystal\nHello\nWorld\n```", "<pre><code class='language-crystal'>Hello\nWorld</code></pre>"
+  assert_render "```crystal\nHello\nWorld\n```", %(<pre><code class="language-crystal">Hello\nWorld</code></pre>)
   assert_render "Hello\n```\nWorld\n```", "<p>Hello</p>\n\n<pre><code>World</code></pre>"
   assert_render "```\n---\n```", "<pre><code>---</code></pre>"
 
diff --git a/src/markdown/html_renderer.cr b/src/markdown/html_renderer.cr
index ecea100bdf45..093a1a3c186f 100644
--- a/src/markdown/html_renderer.cr
+++ b/src/markdown/html_renderer.cr
@@ -54,7 +54,7 @@ class Markdown::HTMLRenderer
     if language.nil?
       @io << "<pre><code>"
     else
-      @io << "<pre><code class='language-#{language}'>"
+      @io << %(<pre><code class="language-#{language}">)
     end
   end