diff --git a/ox-blackfriday.el b/ox-blackfriday.el
index b72ae50..104be01 100644
--- a/ox-blackfriday.el
+++ b/ox-blackfriday.el
@@ -384,6 +384,15 @@ style tag."
                             "")))))
     ret))
 
+;;;; Sanitize URL
+(defun org-blackfriday-url-sanitize (url)
+  "Sanitize the URL by replace certain characters with their hex encoding.
+
+Replaces \"_\" with \"%5F\".
+
+Workaround for Blackfriday bug https://github.com/russross/blackfriday/issues/278."
+  (replace-regexp-in-string "_" "%5F" url))
+
 
 
 ;;; Transcode Functions
diff --git a/ox-hugo.el b/ox-hugo.el
index 7ba0901..c25e687 100644
--- a/ox-hugo.el
+++ b/ox-hugo.el
@@ -1692,9 +1692,13 @@ INFO is a plist used as a communication channel.
 
 Unlike `org-md-link', this function will also copy local images
 and rewrite link paths to make blogging more seamless."
-  (let ((raw-link (org-element-property :raw-link link))
-        (raw-path (org-element-property :path link))
-        (type (org-element-property :type link)))
+  (let* ((raw-link (org-element-property :raw-link link))
+         (raw-path (org-element-property :path link))
+         (type (org-element-property :type link))
+         (link-is-url (member type '("http" "https" "ftp" "mailto"))))
+    (when (and (stringp raw-path)
+               link-is-url)
+      (setq raw-path (org-blackfriday-url-sanitize raw-path)))
     ;; (message "[ox-hugo-link DBG] link: %S" link)
     ;; (message "[ox-hugo-link DBG] link path: %s" (org-element-property :path link))
     ;; (message "[ox-hugo-link DBG] link filename: %s" (expand-file-name (plist-get (car (cdr link)) :path)))
@@ -1767,7 +1771,7 @@ and rewrite link paths to make blogging more seamless."
                                 grand-parent
                               parent))
              (inline-image (not (org-html-standalone-image-p useful-parent info)))
-             (source (if (member type '("http" "https" "ftp"))
+             (source (if link-is-url
                          (concat type ":" path)
                        path))
              (attr (org-export-read-attribute :attr_html useful-parent))
@@ -1861,7 +1865,7 @@ and rewrite link paths to make blogging more seamless."
      (t
       (let* ((link-param-str "")
              (path (cond
-                    ((member type '("http" "https" "ftp" "mailto"))
+                    (link-is-url
                      ;; Taken from ox-html.el -- Extract attributes
                      ;; from parent's paragraph.  HACK: Only do this
                      ;; for the first link in parent (inner image link
diff --git a/test/site/content-org/all-posts.org b/test/site/content-org/all-posts.org
index e8d52c9..1e0e91e 100644
--- a/test/site/content-org/all-posts.org
+++ b/test/site/content-org/all-posts.org
@@ -1994,6 +1994,22 @@ And these ones should be eventually removed and _underline_ the text
 - /This is italics, and *this is bold too*, and back to plain
   italics./
 - *This is bold, and /this is italics too/, and back to plain bold.*
+** Italicize links with underscores                 :italic:links:underscore:
+:PROPERTIES:
+:EXPORT_FILE_NAME: italicize-links-with-underscores
+:END:
+#+begin_description
+Test that links with underscores can be italicized/emboldened/both.
+#+end_description
+{{{oxhugoissue(170)}}}
+*** External links
+- Italic :: /What is a [[https://en.wikipedia.org/wiki/Two%27s_complement][two's complement]]?/
+- Bold :: *What is a [[https://en.wikipedia.org/wiki/Two%27s_complement][two's complement]]?*
+- Bold + Italic :: /*What is a [[https://en.wikipedia.org/wiki/Two%27s_complement][two's complement]]?*/
+*** Internal links
+- Italic :: /Link to [[file:single-posts/post_with_underscore_in_name.org][another post on this site]]?/
+- Bold :: *Link to [[file:single-posts/post_with_underscore_in_name.org][another post on this site]]?*
+- Bold + Italic :: /*Link to [[file:single-posts/post_with_underscore_in_name.org][another post on this site]]?*/
 ** Single and Double quotes
 :PROPERTIES:
 :EXPORT_FILE_NAME: single-double-quotes
diff --git a/test/site/content-org/single-posts/post_with_underscore_in_name.org b/test/site/content-org/single-posts/post_with_underscore_in_name.org
new file mode 100644
index 0000000..e2f1171
--- /dev/null
+++ b/test/site/content-org/single-posts/post_with_underscore_in_name.org
@@ -0,0 +1,12 @@
+#+title: Post with underscore in name
+#+author:
+#+date: 2017-07-20
+
+#+hugo_base_dir: ../../
+#+hugo_section: singles
+#+hugo_tags: "cross-link"
+#+description: Test post to test another ox-hugo test.
+
+This test post is created to test [{{< relref
+"italicize-links-with-underscores" >}}]({{< relref
+"italicize-links-with-underscores" >}}).
diff --git a/test/site/content/posts/figure-shortcode-and-attr-html.md b/test/site/content/posts/figure-shortcode-and-attr-html.md
index 819abb7..dabfee3 100644
--- a/test/site/content/posts/figure-shortcode-and-attr-html.md
+++ b/test/site/content/posts/figure-shortcode-and-attr-html.md
@@ -16,7 +16,7 @@ draft = false
 
 ## Setting `alt` parameter {#setting-alt-parameter}
 
-[Reference](https://www.reddit.com/r/emacs/comments/71wy6n/orgmode_as_a_markup_language_does_make_sense_even/dnhqudn/)
+[Reference](https://www.reddit.com/r/emacs/comments/71wy6n/orgmode%5Fas%5Fa%5Fmarkup%5Flanguage%5Fdoes%5Fmake%5Fsense%5Feven/dnhqudn/)
 
 {{< figure src="/images/org-mode-unicorn-logo.png" alt="Org-mode Unicorn Logo" >}}
 
@@ -59,7 +59,7 @@ to the text that follows that image too._
 
 ### Setting `:width` parameter {#setting-width-parameter}
 
-The image [width](https://www.w3schools.com/tags/att_img_width.asp) can be specified in **pixels** using the `:width`
+The image [width](https://www.w3schools.com/tags/att%5Fimg%5Fwidth.asp) can be specified in **pixels** using the `:width`
 parameter. **The height of the image will be resized proportionally.**
 
 Below image is shown 50 pixels wide.
@@ -85,7 +85,7 @@ image is 200px × 200px. But the image will still show up in 1000px ×
 
 ---
 
-The image [height](https://www.w3schools.com/tags/att_img_height.asp) can be specified in **pixels** using the `:height`
+The image [height](https://www.w3schools.com/tags/att%5Fimg%5Fheight.asp) can be specified in **pixels** using the `:height`
 parameter. **The weight of the image will be resized proportionally.**
 
 Below image is shown 50 pixels tall.
@@ -137,7 +137,7 @@ Rendered this:
 
 **NOTE**: We cannot use `:style` in `#+attr_html` because Hugo does not
  _yet_ support a `style` argument in the `figure` shortcode
- [[Source](https://github.com/gohugoio/hugo/blob/488631fe0abc3667355345c7eb98ba7a2204deb5/tpl/tplimpl/template_embedded.go#L22-L37)].
+ [[Source](https://github.com/gohugoio/hugo/blob/488631fe0abc3667355345c7eb98ba7a2204deb5/tpl/tplimpl/template%5Fembedded.go#L22-L37)].
 
 So using `#+html: <style>.foo img ... </style>` and `#+attr_html: :class
  foo` as shown in the workaround above.
diff --git a/test/site/content/posts/italicize-links-with-underscores.md b/test/site/content/posts/italicize-links-with-underscores.md
new file mode 100644
index 0000000..8bba700
--- /dev/null
+++ b/test/site/content/posts/italicize-links-with-underscores.md
@@ -0,0 +1,32 @@
++++
+title = "Italicize links with underscores"
+description = "Test that links with underscores can be italicized/emboldened/both."
+tags = ["body", "italic", "links", "underscore"]
+draft = false
++++
+
+`ox-hugo` Issue #[170](https://github.com/kaushalmodi/ox-hugo/issues/170)
+
+
+## External links {#external-links}
+
+Italic
+: _What is a [two's complement](https://en.wikipedia.org/wiki/Two%27s%5Fcomplement)?_
+
+Bold
+: **What is a [two's complement](https://en.wikipedia.org/wiki/Two%27s%5Fcomplement)?**
+
+Bold + Italic
+: _**What is a [two's complement](https://en.wikipedia.org/wiki/Two%27s%5Fcomplement)?**_
+
+
+## Internal links {#internal-links}
+
+Italic
+: _Link to [another post on this site]({{< relref "post_with_underscore_in_name" >}})?_
+
+Bold
+: **Link to [another post on this site]({{< relref "post_with_underscore_in_name" >}})?**
+
+Bold + Italic
+: _**Link to [another post on this site]({{< relref "post_with_underscore_in_name" >}})?**_
diff --git a/test/site/content/posts/no-toc-in-summary--with-more.md b/test/site/content/posts/no-toc-in-summary--with-more.md
index bcc688e..1557fd9 100644
--- a/test/site/content/posts/no-toc-in-summary--with-more.md
+++ b/test/site/content/posts/no-toc-in-summary--with-more.md
@@ -33,7 +33,7 @@ HTML comment **`<!--endtoc-->`** after the TOC.
 
 ## Snippet {#snippet}
 
-As the `more` comment is present, the [`summary_minus_toc.html`](https://github.com/kaushalmodi/hugo-bare-min-theme/blob/master/layouts/partials/summary_minus_toc.html) partial
+As the `more` comment is present, the [`summary_minus_toc.html`](https://github.com/kaushalmodi/hugo-bare-min-theme/blob/master/layouts/partials/summary%5Fminus%5Ftoc.html) partial
 used for this test site ensures that only the content between
 `<!--endtoc-->` and `<!--more-->` is considered as summary.
 
diff --git a/test/site/content/posts/no-toc-in-summary--without-more.md b/test/site/content/posts/no-toc-in-summary--without-more.md
index 6a31623..88bc8ab 100644
--- a/test/site/content/posts/no-toc-in-summary--without-more.md
+++ b/test/site/content/posts/no-toc-in-summary--without-more.md
@@ -31,7 +31,7 @@ HTML comment **`<!--endtoc-->`** after the TOC.
 
 ## Snippet {#snippet}
 
-As the `more` comment is not present, the [`summary_minus_toc.html`](https://github.com/kaushalmodi/hugo-bare-min-theme/blob/master/layouts/partials/summary_minus_toc.html)
+As the `more` comment is not present, the [`summary_minus_toc.html`](https://github.com/kaushalmodi/hugo-bare-min-theme/blob/master/layouts/partials/summary%5Fminus%5Ftoc.html)
 partial used for this test site ensures that only the first 300 (or
 so) characters after `<!--endtoc-->` is considered as summary.
 
diff --git a/test/site/content/real-examples/nn-intro.md b/test/site/content/real-examples/nn-intro.md
index e32db75..462e5df 100644
--- a/test/site/content/real-examples/nn-intro.md
+++ b/test/site/content/real-examples/nn-intro.md
@@ -579,7 +579,7 @@ if __name__ == '__main__':
     net.gradient_descent(train_data, test_data, epoches=100, m=10, eta=2.0)
 ```
 
-数据加载脚本： [`mnist_loader.py`](https://github.com/mnielsen/neural-networks-and-deep-learning/blob/master/src/mnist_loader.py)
+数据加载脚本： [`mnist_loader.py`](https://github.com/mnielsen/neural-networks-and-deep-learning/blob/master/src/mnist%5Floader.py)
 。输入数据为二元组列表： `(input(784,1), output(10,1))`
 
 ```sh
@@ -852,7 +852,7 @@ Round {30}: {9802}/{10000}
 
 对于MNIST数字分类任务，目前最好的准确率为99.79%，那些识别错误的case，恐怕人类想
 要正确识别也很困难。神经网络的分类效果最新进展可以参看这里：
-[classification\\\_datasets\\\_results](http://rodrigob.github.io/are_we_there_yet/build/classification_datasets_results.html)。
+[classification\\\_datasets\\\_results](http://rodrigob.github.io/are%5Fwe%5Fthere%5Fyet/build/classification%5Fdatasets%5Fresults.html)。
 
 本文是tensorflow官方推荐教程：[Neural Networks and Deep Learning](http://neuralnetworksanddeeplearning.com/)的笔记整理，原文
 [Github Page](https://github.com/Vonng/Math/blob/master/nndl/nn-intro.md)。
diff --git a/test/site/content/singles/post_with_underscore_in_name.md b/test/site/content/singles/post_with_underscore_in_name.md
new file mode 100644
index 0000000..b3a9c11
--- /dev/null
+++ b/test/site/content/singles/post_with_underscore_in_name.md
@@ -0,0 +1,11 @@
++++
+title = "Post with underscore in name"
+description = "Test post to test another ox-hugo test."
+date = 2017-07-20
+tags = ["cross-link"]
+draft = false
++++
+
+This test post is created to test [{{< relref
+"italicize-links-with-underscores" >}}]({{< relref
+"italicize-links-with-underscores" >}}).