diff --git a/src/applications/differential/parser/changeset/DifferentialChangesetParser.php b/src/applications/differential/parser/changeset/DifferentialChangesetParser.php
index 6a15fb9a52..edc6153d08 100644
--- a/src/applications/differential/parser/changeset/DifferentialChangesetParser.php
+++ b/src/applications/differential/parser/changeset/DifferentialChangesetParser.php
@@ -27,7 +27,6 @@ class DifferentialChangesetParser {
   protected $parsedHunk   = false;
 
   protected $filename     = null;
-  protected $filetype     = null;
   protected $missingOld   = array();
   protected $missingNew   = array();
 
@@ -161,10 +160,7 @@ class DifferentialChangesetParser {
 
   public function setFilename($filename) {
     $this->filename = $filename;
-    if (strpos($filename, '.', 1) !== false) {
-      $parts = explode('.', $filename);
-      $this->filetype = end($parts);
-    }
+    return $this;
   }
 
   public function setHandles(array $handles) {
@@ -723,7 +719,7 @@ class DifferentialChangesetParser {
 
   protected function getHighlightFuture($corpus) {
     return $this->highlightEngine->getHighlightFuture(
-      $this->filetype,
+      $this->highlightEngine->getLanguageFromFilename($this->filename),
       $corpus);
   }
 
diff --git a/src/applications/diffusion/controller/file/DiffusionBrowseFileController.php b/src/applications/diffusion/controller/file/DiffusionBrowseFileController.php
index c0b3402547..3bf7e7ee3b 100644
--- a/src/applications/diffusion/controller/file/DiffusionBrowseFileController.php
+++ b/src/applications/diffusion/controller/file/DiffusionBrowseFileController.php
@@ -179,13 +179,16 @@ class DiffusionBrowseFileController extends DiffusionController {
 
         list($text_list, $rev_list, $blame_dict) = $file_query->getBlameData();
 
-        $highlightEngine = new PhutilDefaultSyntaxHighlighterEngine();
-        $highlightEngine->setConfig(
+        $highlight_engine = new PhutilDefaultSyntaxHighlighterEngine();
+        $highlight_engine->setConfig(
           'pygments.enabled',
           PhabricatorEnv::getEnvConfig('pygments.enabled'));
 
-        $text_list = explode("\n", $highlightEngine->highlightSource($path,
-          implode("\n", $text_list)));
+        $text_list = explode(
+          "\n",
+          $highlight_engine->highlightSource(
+            $highlight_engine->getLanguageFromFilename($path),
+            implode("\n", $text_list)));
 
         $rows = $this->buildDisplayRows($text_list, $rev_list, $blame_dict,
           $needs_blame, $drequest, $file_query, $selected);
diff --git a/src/applications/paste/controller/view/PhabricatorPasteViewController.php b/src/applications/paste/controller/view/PhabricatorPasteViewController.php
index 776eacea5f..2809395853 100644
--- a/src/applications/paste/controller/view/PhabricatorPasteViewController.php
+++ b/src/applications/paste/controller/view/PhabricatorPasteViewController.php
@@ -89,14 +89,22 @@ class PhabricatorPasteViewController extends PhabricatorPasteController {
     require_celerity_resource('diffusion-source-css');
     require_celerity_resource('syntax-highlighting-css');
 
-    $highlightEngine = new PhutilDefaultSyntaxHighlighterEngine();
-    $highlightEngine->setConfig(
+    $highlight_engine = new PhutilDefaultSyntaxHighlighterEngine();
+    $highlight_engine->setConfig(
       'pygments.enabled',
       PhabricatorEnv::getEnvConfig('pygments.enabled'));
 
+
+    $language = $paste->getLanguage();
+    if (empty($language)) {
+      $language = $highlight_engine->getLanguageFromFilename(
+        $paste->getTitle());
+    }
+
     $text_list = explode(
-      "\n", $highlightEngine->highlightSource(
-        nonempty($paste->getLanguage(), $paste->getTitle()),
+      "\n",
+      $highlight_engine->highlightSource(
+        $language,
         $file->loadFileData()));
 
     $rows = $this->buildDisplayRows($text_list);