diff --git a/resources/sql/autopatches/20171101.diff.01.active.sql b/resources/sql/autopatches/20171101.diff.01.active.sql
new file mode 100644
index 0000000000..aee8c5aa13
--- /dev/null
+++ b/resources/sql/autopatches/20171101.diff.01.active.sql
@@ -0,0 +1,2 @@
+ALTER TABLE {$NAMESPACE}_differential.differential_revision
+  ADD activeDiffPHID VARBINARY(64) NOT NULL;
diff --git a/resources/sql/autopatches/20171101.diff.02.populate.php b/resources/sql/autopatches/20171101.diff.02.populate.php
new file mode 100644
index 0000000000..b41b0aa51d
--- /dev/null
+++ b/resources/sql/autopatches/20171101.diff.02.populate.php
@@ -0,0 +1,24 @@
+<?php
+
+$table = new DifferentialRevision();
+$conn = $table->establishConnection('w');
+$diff_table = new DifferentialDiff();
+
+foreach (new LiskMigrationIterator($table) as $revision) {
+  $revision_id = $revision->getID();
+
+  $diff_row = queryfx_one(
+    $conn,
+    'SELECT phid FROM %T WHERE revisionID = %d ORDER BY id DESC LIMIT 1',
+    $diff_table->getTableName(),
+    $revision_id);
+
+  if ($diff_row) {
+    queryfx(
+      $conn,
+      'UPDATE %T SET activeDiffPHID = %s WHERE id = %d',
+      $table->getTableName(),
+      $diff_row['phid'],
+      $revision_id);
+  }
+}
diff --git a/src/applications/differential/editor/DifferentialTransactionEditor.php b/src/applications/differential/editor/DifferentialTransactionEditor.php
index 79a582a43f..3e6cca1edb 100644
--- a/src/applications/differential/editor/DifferentialTransactionEditor.php
+++ b/src/applications/differential/editor/DifferentialTransactionEditor.php
@@ -138,8 +138,7 @@ final class DifferentialTransactionEditor
           $object->setRepositoryPHID($diff->getRepositoryPHID());
         }
         $object->attachActiveDiff($diff);
-
-        // TODO: Update the `diffPHID` once we add that.
+        $object->setActiveDiffPHID($diff->getPHID());
         return;
     }
 
diff --git a/src/applications/differential/storage/DifferentialRevision.php b/src/applications/differential/storage/DifferentialRevision.php
index 467e503f6f..61f934f13b 100644
--- a/src/applications/differential/storage/DifferentialRevision.php
+++ b/src/applications/differential/storage/DifferentialRevision.php
@@ -35,6 +35,8 @@ final class DifferentialRevision extends DifferentialDAO
   protected $mailKey;
   protected $branchName;
   protected $repositoryPHID;
+  protected $activeDiffPHID;
+
   protected $viewPolicy = PhabricatorPolicies::POLICY_USER;
   protected $editPolicy = PhabricatorPolicies::POLICY_USER;
   protected $properties = array();