diff --git a/src/applications/differential/render/DifferentialChangesetHTMLRenderer.php b/src/applications/differential/render/DifferentialChangesetHTMLRenderer.php
--- a/src/applications/differential/render/DifferentialChangesetHTMLRenderer.php
+++ b/src/applications/differential/render/DifferentialChangesetHTMLRenderer.php
@@ -409,16 +409,8 @@
           $content)));
   }
 
-  private function renderColgroup() {
-    return phutil_tag('colgroup', array(), array(
-      phutil_tag('col', array('class' => 'num')),
-      phutil_tag('col', array('class' => 'left')),
-      phutil_tag('col', array('class' => 'num')),
-      phutil_tag('col', array('class' => 'copy')),
-      phutil_tag('col', array('class' => 'right')),
-      phutil_tag('col', array('class' => 'cov')),
-    ));
-  }
+  abstract protected function renderColgroup();
+
 
   protected function wrapChangeInTable($content) {
     if (!$content) {
diff --git a/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php b/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php
--- a/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php
+++ b/src/applications/differential/render/DifferentialChangesetOneUpRenderer.php
@@ -7,6 +7,14 @@
     return true;
   }
 
+  protected function renderColgroup() {
+    return phutil_tag('colgroup', array(), array(
+      phutil_tag('col', array('class' => 'num')),
+      phutil_tag('col', array('class' => 'num')),
+      phutil_tag('col', array('class' => 'unified')),
+    ));
+  }
+
   public function renderTextChange(
     $range_start,
     $range_len,
diff --git a/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php b/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php
--- a/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php
+++ b/src/applications/differential/render/DifferentialChangesetTwoUpRenderer.php
@@ -7,6 +7,17 @@
     return false;
   }
 
+  protected function renderColgroup() {
+    return phutil_tag('colgroup', array(), array(
+      phutil_tag('col', array('class' => 'num')),
+      phutil_tag('col', array('class' => 'left')),
+      phutil_tag('col', array('class' => 'num')),
+      phutil_tag('col', array('class' => 'copy')),
+      phutil_tag('col', array('class' => 'right')),
+      phutil_tag('col', array('class' => 'cov')),
+    ));
+  }
+
   public function renderTextChange(
     $range_start,
     $range_len,