diff --git a/browser/components/MarkdownPreview.js b/browser/components/MarkdownPreview.js
index 124bd8c30..c3d3a7305 100755
--- a/browser/components/MarkdownPreview.js
+++ b/browser/components/MarkdownPreview.js
@@ -219,7 +219,7 @@ export default class MarkdownPreview extends React.Component {
       const {fontFamily, fontSize, codeBlockFontFamily, lineNumber, codeBlockTheme, scrollPastEnd, theme, allowCustomCSS, customCSS} = this.getStyleParams()
 
       const inlineStyles = buildStyle(fontFamily, fontSize, codeBlockFontFamily, lineNumber, scrollPastEnd, theme, allowCustomCSS, customCSS)
-      let body = this.markdown.render(escapeHtmlCharacters(noteContent))
+      let body = this.markdown.render(escapeHtmlCharacters(noteContent, { detectCodeBlock: true }))
 
       const files = [this.GetCodeThemeLink(codeBlockTheme), ...CSS_FILES]
       const attachmentsAbsolutePaths = attachmentManagement.getAbsolutePathsOfAttachmentsInContent(noteContent, this.props.storagePath)
@@ -412,7 +412,7 @@ export default class MarkdownPreview extends React.Component {
         value = value.replace(codeBlock, htmlTextHelper.encodeEntities(codeBlock))
       })
     }
-    let renderedHTML = this.markdown.render(value)
+    const renderedHTML = this.markdown.render(value)
     attachmentManagement.migrateAttachments(renderedHTML, storagePath, noteKey)
     this.refs.root.contentWindow.document.body.innerHTML = attachmentManagement.fixLocalURLS(renderedHTML, storagePath)
 
diff --git a/browser/lib/markdown.js b/browser/lib/markdown.js
index 4dafa4a3a..931697a38 100644
--- a/browser/lib/markdown.js
+++ b/browser/lib/markdown.js
@@ -245,4 +245,3 @@ class Markdown {
 }
 
 export default Markdown
-
diff --git a/browser/lib/utils.js b/browser/lib/utils.js
index 441cfbc7a..564ed3d25 100644
--- a/browser/lib/utils.js
+++ b/browser/lib/utils.js
@@ -6,52 +6,64 @@ export function lastFindInArray (array, callback) {
   }
 }
 
-export function escapeHtmlCharacters (text) {
-  const matchHtmlRegExp = /["'&<>]/
-  const str = '' + text
-  const match = matchHtmlRegExp.exec(str)
+export function escapeHtmlCharacters (html, opt = { detectCodeBlock: false }) {
+  const matchHtmlRegExp = /["'&<>]/g
+  const escapes = ['&quot;', '&amp;', '&#39;', '&lt;', '&gt;']
+  let match = null
+  const replaceAt = (str, index, replace) =>
+    str.substr(0, index) +
+    replace +
+    str.substr(index + replace.length - (replace.length - 1))
 
-  if (!match) {
-    return str
-  }
-
-  let escape
-  let html = ''
-  let index = 0
-  let lastIndex = 0
-
-  for (index = match.index; index < str.length; index++) {
-    switch (str.charCodeAt(index)) {
-      case 34: // "
-        escape = '&quot;'
-        break
-      case 38: // &
-        escape = '&amp;'
-        break
-      case 39: // '
-        escape = '&#39;'
-        break
-      case 60: // <
-        escape = '&lt;'
-        break
-      case 62: // >
-        escape = '&gt;'
-        break
-      default:
+  // detecting code block
+  while ((match = matchHtmlRegExp.exec(html)) != null) {
+    const current = { char: match[0], index: match.index }
+    if (opt.detectCodeBlock) {
+      // position of the nearest line start
+      let previousLineEnd = current.index - 1
+      while (html[previousLineEnd] !== '\n' && previousLineEnd !== -1) {
+        previousLineEnd--
+      }
+      // 4 spaces means this character is in a code block
+      if (
+        html[previousLineEnd + 1] === ' ' &&
+        html[previousLineEnd + 2] === ' ' &&
+        html[previousLineEnd + 3] === ' ' &&
+        html[previousLineEnd + 4] === ' '
+      ) {
+        // so skip it
         continue
+      }
     }
-
-    if (lastIndex !== index) {
-      html += str.substring(lastIndex, index)
+    // otherwise, escape it !!!
+    if (current.char === '&') {
+      let nextStr = ''
+      let nextIndex = current.index
+      let escapedStr = false
+      // maximum length of an escape string is 5. For example ('&quot;')
+      while (nextStr.length <= 5) {
+        nextStr += html[nextIndex]
+        nextIndex++
+        if (escapes.indexOf(nextStr) !== -1) {
+          escapedStr = true
+          break
+        }
+      }
+      if (!escapedStr) {
+        // this & char is not a part of an escaped string
+        html = replaceAt(html, current.index, '&amp;')
+      }
+    } else if (current.char === '"') {
+      html = replaceAt(html, current.index, '&quot;')
+    } else if (current.char === "'") {
+      html = replaceAt(html, current.index, '&#39;')
+    } else if (current.char === '<') {
+      html = replaceAt(html, current.index, '&lt;')
+    } else if (current.char === '>') {
+      html = replaceAt(html, current.index, '&gt;')
     }
-
-    lastIndex = index + 1
-    html += escape
   }
-
-  return lastIndex !== index
-      ? html + str.substring(lastIndex, index)
-      : html
+  return html
 }
 
 export function isObjectEqual (a, b) {
diff --git a/tests/lib/escapeHtmlCharacters-test.js b/tests/lib/escapeHtmlCharacters-test.js
new file mode 100644
index 000000000..f13ab2975
--- /dev/null
+++ b/tests/lib/escapeHtmlCharacters-test.js
@@ -0,0 +1,48 @@
+const { escapeHtmlCharacters } = require('browser/lib/utils')
+const test = require('ava')
+
+test('escapeHtmlCharacters should return the original string if nothing needed to escape', t => {
+  const input = 'Nothing to be escaped'
+  const expected = 'Nothing to be escaped'
+  const actual = escapeHtmlCharacters(input)
+  t.is(actual, expected)
+})
+
+test('escapeHtmlCharacters should skip code block if that option is enabled', t => {
+  const input = `    <no escape>
+<escapeMe>`
+  const expected = `    <no escape>
+&lt;escapeMe&gt;`
+  const actual = escapeHtmlCharacters(input, { detectCodeBlock: true })
+  t.is(actual, expected)
+})
+
+test('escapeHtmlCharacters should NOT skip character not in code block but start with 4 spaces', t => {
+  const input = '4 spaces    &'
+  const expected = '4 spaces    &amp;'
+  const actual = escapeHtmlCharacters(input, { detectCodeBlock: true })
+  t.is(actual, expected)
+})
+
+test('escapeHtmlCharacters should NOT skip code block if that option is NOT enabled', t => {
+  const input = `    <no escape>
+<escapeMe>`
+  const expected = `    &lt;no escape&gt;
+&lt;escapeMe&gt;`
+  const actual = escapeHtmlCharacters(input)
+  t.is(actual, expected)
+})
+
+test('escapeHtmlCharacters should NOT escape & character if it\'s a part of an escaped character', t => {
+  const input = 'Do not escape &amp; or &quot; but do escape &'
+  const expected = 'Do not escape &amp; or &quot; but do escape &amp;'
+  const actual = escapeHtmlCharacters(input)
+  t.is(actual, expected)
+})
+
+test('escapeHtmlCharacters should return the correct result', t => {
+  const input = '& < > " \''
+  const expected = '&amp; &lt; &gt; &quot; &#39;'
+  const actual = escapeHtmlCharacters(input)
+  t.is(actual, expected)
+})