diff --git a/src/infrastructure/markup/remarkup/__tests__/PhutilRemarkupEngineTestCase.php b/src/infrastructure/markup/remarkup/__tests__/PhutilRemarkupEngineTestCase.php
--- a/src/infrastructure/markup/remarkup/__tests__/PhutilRemarkupEngineTestCase.php
+++ b/src/infrastructure/markup/remarkup/__tests__/PhutilRemarkupEngineTestCase.php
@@ -8,6 +8,14 @@
 final class PhutilRemarkupEngineTestCase extends PhutilTestCase {
 
   public function testEngine() {
+    // Setup test configurations.
+    // Taken from PhabricatorEnvTestCase.
+    // TODO: this crashes :D Call to a member function pushSource() on null
+    $env = PhabricatorEnv::beginScopedEnv();
+    $env->overrideEnvConfig(
+      'phabricator.production-uri',
+      'https://phorge.localhost');
+
     $root = dirname(__FILE__).'/remarkup/';
     foreach (Filesystem::listDirectory($root, $hidden = false) as $file) {
       $this->markupText($root.$file);
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-brackets.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-brackets.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-brackets.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-brackets.txt
@@ -1,5 +1,5 @@
 <http://www.zany.com/omg/weird_url,,,>
 ~~~~~~~~~~
-<p><a href="http://www.zany.com/omg/weird_url,,," class="remarkup-link" target="_blank" rel="noreferrer">http://www.zany.com/omg/weird_url,,,</a></p>
+<p><a href="http://www.zany.com/omg/weird_url,,," class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.zany.com/omg/weird_url,,,</a></p>
 ~~~~~~~~~~
 http://www.zany.com/omg/weird_url,,,
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-edge-cases.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-edge-cases.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-edge-cases.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-edge-cases.txt
@@ -10,17 +10,17 @@
 
 Quick! http://www.example.com/!
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
 
-<p>(<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>)</p>
+<p>(<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>)</p>
 
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
 
-<p><a href="http://www.example.com/wiki/example_(disambiguation)" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/wiki/example_(disambiguation)</a></p>
+<p><a href="http://www.example.com/wiki/example_(disambiguation)" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/wiki/example_(disambiguation)</a></p>
 
-<p>(example <a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>)</p>
+<p>(example <a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>)</p>
 
-<p>Quick! <a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>!</p>
+<p>Quick! <a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>!</p>
 ~~~~~~~~~~
 http://www.example.com/
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mixed.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mixed.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mixed.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-mixed.txt
@@ -5,11 +5,11 @@
 <http://www.example.com/ [[http://www.example.net/ | Example]]>
 
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">Example</a>(<a href="http://www.alternate.org/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.alternate.org/</a>)</p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">Example</a>(<a href="http://www.alternate.org/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.alternate.org/</a>)</p>
 
-<p>(<a href="http://www.alternate.org/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.alternate.org/</a>)<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">Example</a></p>
+<p>(<a href="http://www.alternate.org/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.alternate.org/</a>)<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">Example</a></p>
 
-<p>&lt;<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a> <a href="http://www.example.net/" class="remarkup-link" target="_blank" rel="noreferrer">Example</a>&gt;</p>
+<p>&lt;<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a> <a href="http://www.example.net/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">Example</a>&gt;</p>
 ~~~~~~~~~~
 Example <http://www.example.com/>(http://www.alternate.org/)
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-same-window.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-same-window.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-same-window.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-same-window.txt
@@ -2,9 +2,9 @@
 
 http://www.example.com/
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" rel="noreferrer">http://www.example.com/</a></p>
 
-<p><a href="http://www.example.com/" class="remarkup-link" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" rel="noreferrer">http://www.example.com/</a></p>
 ~~~~~~~~~~
 http://www.example.com/
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-square.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-square.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-square.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-square.txt
@@ -8,15 +8,15 @@
 
 [[#anchor | Anchors ]]
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a></p>
 
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">example.com</a></p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">example.com</a></p>
 
-<p><a href="http://www.example.com/x/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/x/</a></p>
+<p><a href="http://www.example.com/x/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/x/</a></p>
 
-<p><a href="http://www.example.com/page/#anchor" class="remarkup-link" rel="noreferrer">http://www.example.com/page/#anchor</a></p>
+<p><a href="http://www.example.com/page/#anchor" class="remarkup-link remarkup-link-ext" rel="noreferrer">http://www.example.com/page/#anchor</a></p>
 
-<p><a href="http://www.example.com/page/#anchor" class="remarkup-link" rel="noreferrer">Anchors</a></p>
+<p><a href="http://www.example.com/page/#anchor" class="remarkup-link remarkup-link-ext" rel="noreferrer">Anchors</a></p>
 ~~~~~~~~~~
 http://www.example.com/
 
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-punctuation.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-punctuation.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-punctuation.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-punctuation.txt
@@ -2,8 +2,8 @@
 http://www.example.com/..
 http://www.example.com/!!!
 ~~~~~~~~~~
-<p><a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>,
-<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>..
-<a href="http://www.example.com/" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/</a>!!!</p>
+<p><a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>,
+<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>..
+<a href="http://www.example.com/" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/</a>!!!</p>
 ~~~~~~~~~~
 http://www.example.com/, http://www.example.com/.. http://www.example.com/!!!
diff --git a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-tilde.txt b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-tilde.txt
--- a/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-tilde.txt
+++ b/src/infrastructure/markup/remarkup/__tests__/remarkup/link-with-tilde.txt
@@ -1,5 +1,5 @@
 http://www.example.com/~~
 ~~~~~~~~~~
-<p><a href="http://www.example.com/~" class="remarkup-link" target="_blank" rel="noreferrer">http://www.example.com/~</a></p>
+<p><a href="http://www.example.com/~" class="remarkup-link remarkup-link-ext" target="_blank" rel="noreferrer">http://www.example.com/~</a></p>
 ~~~~~~~~~~
 http://www.example.com/~~