diff --git a/browser/components/MarkdownPreview.js b/browser/components/MarkdownPreview.js
index ae2bdea2c..537ebe38b 100755
--- a/browser/components/MarkdownPreview.js
+++ b/browser/components/MarkdownPreview.js
@@ -421,9 +421,9 @@ export default class MarkdownPreview extends React.Component {
         el.innerHTML = ''
         if (codeBlockTheme.indexOf('solarized') === 0) {
           const [refThema, color] = codeBlockTheme.split(' ')
-          el.parentNode.className += ` cm-s-${refThema} cm-s-${color} CodeMirror`
+          el.parentNode.className += ` cm-s-${refThema} cm-s-${color}`
         } else {
-          el.parentNode.className += ` cm-s-${codeBlockTheme} CodeMirror`
+          el.parentNode.className += ` cm-s-${codeBlockTheme}`
         }
         CodeMirror.runMode(content, syntax.mime, el, {
           tabSize: indentSize
diff --git a/browser/lib/markdown.js b/browser/lib/markdown.js
index b97f9d562..bfe621f7f 100644
--- a/browser/lib/markdown.js
+++ b/browser/lib/markdown.js
@@ -39,7 +39,7 @@ var md = markdownit({
     if (langType === 'sequence') {
       return `<pre class="sequence">${str}</pre>`
     }
-    return '<pre class="code">' +
+    return '<pre class="code CodeMirror">' +
       '<span class="filename">' + fileName + '</span>' +
       createGutter(str, firstLineNumber) +
       '<code class="' + langType + '">' +