diff --git a/src/core.ts b/src/core.ts
index 3f324fa..1f074b8 100644
--- a/src/core.ts
+++ b/src/core.ts
@@ -71,8 +71,8 @@ function highlightAuto (md: MarkdownIt, hljs: HLJSApi, ignoreIllegals: boolean,
 function wrapCodeRenderer (renderer: Renderer.RenderRule): Renderer.RenderRule {
   return function wrappedRenderer (...args) {
     return renderer(...args)
-      .replace('<code class="', '<code class="hljs ')
-      .replace('<code>', '<code class="hljs">')
+      .replace(/<code class="/g, '<code class="hljs ')
+      .replace(/<code>/g, '<code class="hljs">')
   }
 }
 
diff --git a/test/test.js b/test/test.js
index 6d85c99..a6226ac 100644
--- a/test/test.js
+++ b/test/test.js
@@ -131,4 +131,24 @@ describe('markdown-it-highlightjs', () => {
       md().use(highlightjs, { inline: true }).use(attrs).renderInline('`console.log(42)`{.js}'),
       '<code class="hljs language-js"><span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-number">42</span>)</code>')
   })
+
+  it('applies hljs class to all code tags', () => {
+    // Define a mock plugin that handles the 'multicode' language
+    const multicodeHlJsPlugin = (md) => {
+      const oldHighlight = md.options.highlight
+      md.options.highlight = (code, lang, attrs) => {
+        if (lang && lang === 'multicode') {
+          return '<pre><code class="language-multicode">A</code><code class="language-multicode-overlay">B</code></pre>'
+        }
+
+        return oldHighlight(code, lang, attrs)
+      }
+    }
+
+    const markdownIt = md()
+    markdownIt.use(highlightjs)
+    markdownIt.use(multicodeHlJsPlugin)
+
+    assert.equal(markdownIt.render('```multicode\n```'), '<pre><code class="hljs language-multicode">A</code><code class="hljs language-multicode-overlay">B</code></pre>\n')
+  })
 })