diff --git a/browser/lib/markdown.js b/browser/lib/markdown.js
index 67a4b530..91a04a2a 100644
--- a/browser/lib/markdown.js
+++ b/browser/lib/markdown.js
@@ -3,6 +3,7 @@ import emoji from 'markdown-it-emoji'
 import math from '@rokt33r/markdown-it-math'
 import _ from 'lodash'
 
+// FIXME We should not depend on global variable.
 const katex = window.katex
 
 function createGutter (str) {
@@ -137,37 +138,9 @@ md.renderer.render = function render (tokens, options, env) {
   let result = originalRender.call(md.renderer, tokens, options, env)
   return result
 }
+// FIXME We should not depend on global variable.
 window.md = md
 
-function strip (input) {
-  var output = input
-  try {
-    output = output
-      .replace(/^([\s\t]*)([\*\-\+]|\d\.)\s+/gm, '$1')
-      .replace(/\n={2,}/g, '\n')
-      .replace(/~~/g, '')
-      .replace(/`{3}.*\n/g, '')
-      .replace(/<(.*?)>/g, '$1')
-      .replace(/^[=\-]{2,}\s*$/g, '')
-      .replace(/\[\^.+?\](: .*?$)?/g, '')
-      .replace(/\s{0,2}\[.*?\]: .*?$/g, '')
-      .replace(/!\[.*?\][\[\(].*?[\]\)]/g, '')
-      .replace(/\[(.*?)\][\[\(].*?[\]\)]/g, '$1')
-      .replace(/>/g, '')
-      .replace(/^\s{1,2}\[(.*?)\]: (\S+)( ".*?")?\s*$/g, '')
-      .replace(/^#{1,6}\s*([^#]*)\s*(#{1,6})?/gm, '$1')
-      .replace(/([\*_]{1,3})(\S.*?\S)\1/g, '$2')
-      .replace(/(`{3,})(.*?)\1/gm, '$2')
-      .replace(/^-{3,}\s*$/g, '')
-      .replace(/`(.+?)`/g, '$1')
-      .replace(/\n{2,}/g, '\n\n')
-  } catch (e) {
-    console.error(e)
-    return input
-  }
-  return output
-}
-
 function normalizeLinkText (linkText) {
   return md.normalizeLinkText(linkText)
 }
@@ -178,7 +151,7 @@ const markdown = {
     const renderedContent = md.render(content)
     return renderedContent
   },
-  strip,
   normalizeLinkText
 }
+
 export default markdown
diff --git a/browser/lib/markdownTextHelper.js b/browser/lib/markdownTextHelper.js
new file mode 100644
index 00000000..1501e2c7
--- /dev/null
+++ b/browser/lib/markdownTextHelper.js
@@ -0,0 +1,39 @@
+/**
+ * @fileoverview Text trimmer for markdown note.
+ */
+
+/**
+ * @param {string} input
+ * @return {string}
+ */
+export function strip (input) {
+  let output = input
+  try {
+    output = output
+      .replace(/^([\s\t]*)([\*\-\+]|\d+\.)\s+/gm, '$1')
+      .replace(/\n={2,}/g, '\n')
+      .replace(/~~/g, '')
+      .replace(/`{3}.*\n/g, '')
+      .replace(/<(.*?)>/g, '$1')
+      .replace(/^[=\-]{2,}\s*$/g, '')
+      .replace(/\[\^.+?\](: .*?$)?/g, '')
+      .replace(/\s{0,2}\[.*?\]: .*?$/g, '')
+      .replace(/!\[.*?\][\[\(].*?[\]\)]/g, '')
+      .replace(/\[(.*?)\][\[\(].*?[\]\)]/g, '$1')
+      .replace(/>/g, '')
+      .replace(/^\s{1,2}\[(.*?)\]: (\S+)( ".*?")?\s*$/g, '')
+      .replace(/^#{1,6}\s*([^#]*)\s*(#{1,6})?/gm, '$1')
+      .replace(/(`{3,})(.*?)\1/gm, '$2')
+      .replace(/^-{3,}\s*$/g, '')
+      .replace(/`(.+?)`/g, '$1')
+      .replace(/\n{2,}/g, '\n\n')
+  } catch (e) {
+    console.error(e)
+    return input
+  }
+  return output
+}
+
+export default {
+  strip
+}
diff --git a/browser/main/Detail/MarkdownNoteDetail.js b/browser/main/Detail/MarkdownNoteDetail.js
index 767f17b3..bc407b62 100644
--- a/browser/main/Detail/MarkdownNoteDetail.js
+++ b/browser/main/Detail/MarkdownNoteDetail.js
@@ -9,7 +9,7 @@ import FolderSelect from './FolderSelect'
 import dataApi from 'browser/main/lib/dataApi'
 import { hashHistory } from 'react-router'
 import ee from 'browser/main/lib/eventEmitter'
-import markdown from 'browser/lib/markdown'
+import markdown from 'browser/lib/markdownTextHelper'
 import StatusBar from '../StatusBar'
 import _ from 'lodash'
 import { findNoteTitle } from 'browser/lib/findNoteTitle'
diff --git a/tests/lib/markdown-text-helper-test.js b/tests/lib/markdown-text-helper-test.js
new file mode 100644
index 00000000..e4ad86bc
--- /dev/null
+++ b/tests/lib/markdown-text-helper-test.js
@@ -0,0 +1,46 @@
+/**
+ * @fileoverview Unit test for browser/lib/markdown
+ */
+const test = require('ava')
+const markdown = require('browser/lib/markdownTextHelper')
+
+test(t => {
+  // [input, expected]
+  const testCases = [
+    // List
+    [' - ', ' '],
+    [' + ', ' '],
+    [' * ', ' '],
+    [' *   ', ' '],
+    [' 1. ', ' '],
+    [' 2.  ', ' '],
+    [' 10. ', ' '],
+    ['\t- ', '\t'],
+    ['- ', ''],
+    // Header with using line
+    ['\n==', '\n'],
+    ['\n===', '\n'],
+    ['test\n===', 'test\n'],
+    // Code block
+    ['```test\n', ''],
+    ['```test\nhoge', 'hoge'],
+    // HTML tag
+    ['<>', ''],
+    ['<test>', 'test'],
+    ['hoge<test>', 'hogetest'],
+    ['<test>moge', 'testmoge'],
+    // Emphasis
+    ['~~', ''],
+    ['~~text~~', 'text'],
+    // Don't remove underscore
+    ['`MY_TITLE`', 'MY_TITLE'],
+    ['MY_TITLE', 'MY_TITLE'],
+    // I have no idea for it...
+    ['```test', '`test']
+  ]
+
+  testCases.forEach(testCase => {
+    const [input, expected] = testCase
+    t.is(markdown.strip(input), expected, `Test for strip() input: ${input} expected: ${expected}`)
+  })
+})