diff --git a/resources/sql/autopatches/20170322.reviewers.04.actor.sql b/resources/sql/autopatches/20170322.reviewers.04.actor.sql
new file mode 100644
index 0000000000..27b46848a7
--- /dev/null
+++ b/resources/sql/autopatches/20170322.reviewers.04.actor.sql
@@ -0,0 +1,2 @@
+ALTER TABLE {$NAMESPACE}_differential.differential_reviewer
+  ADD lastActorPHID VARBINARY(64);
diff --git a/src/applications/differential/storage/DifferentialReviewer.php b/src/applications/differential/storage/DifferentialReviewer.php
index eec05398b6..d43f533b5c 100644
--- a/src/applications/differential/storage/DifferentialReviewer.php
+++ b/src/applications/differential/storage/DifferentialReviewer.php
@@ -8,6 +8,7 @@ final class DifferentialReviewer
   protected $reviewerStatus;
   protected $lastActionDiffPHID;
   protected $lastCommentDiffPHID;
+  protected $lastActorPHID;
 
   private $authority = array();
 
@@ -17,6 +18,7 @@ final class DifferentialReviewer
         'reviewerStatus' => 'text64',
         'lastActionDiffPHID' => 'phid?',
         'lastCommentDiffPHID' => 'phid?',
+        'lastActorPHID' => 'phid?',
       ),
       self::CONFIG_KEY_SCHEMA => array(
         'key_revision' => array(
diff --git a/src/applications/differential/xaction/DifferentialRevisionReviewTransaction.php b/src/applications/differential/xaction/DifferentialRevisionReviewTransaction.php
index a0fe0ea3d0..86aba03e25 100644
--- a/src/applications/differential/xaction/DifferentialRevisionReviewTransaction.php
+++ b/src/applications/differential/xaction/DifferentialRevisionReviewTransaction.php
@@ -198,12 +198,17 @@ abstract class DifferentialRevisionReviewTransaction
             ->setReviewerPHID($dst_phid);
         }
 
+        $old_status = $reviewer->getReviewerStatus();
         $reviewer->setReviewerStatus($status);
 
         if ($diff_phid) {
           $reviewer->setLastActionDiffPHID($diff_phid);
         }
 
+        if ($old_status !== $status) {
+          $reviewer->setLastActorPHID($this->getActingAsPHID());
+        }
+
         try {
           $reviewer->save();
         } catch (AphrontDuplicateKeyQueryException $ex) {