diff --git a/src/applications/differential/field/specification/DifferentialFreeformFieldSpecification.php b/src/applications/differential/field/specification/DifferentialFreeformFieldSpecification.php
index cbb7d657af..62f2731064 100644
--- a/src/applications/differential/field/specification/DifferentialFreeformFieldSpecification.php
+++ b/src/applications/differential/field/specification/DifferentialFreeformFieldSpecification.php
@@ -200,15 +200,27 @@ abstract class DifferentialFreeformFieldSpecification
 
     $message = $this->renderValueForCommitMessage($is_edit = false);
 
-    $commits = self::findRevertedCommits($message);
-
     $user = id(new PhabricatorUser())->loadOneWhere(
       'phid = %s',
       $data->getCommitDetail('authorPHID'));
     if (!$user) {
+      // TODO: Maybe after grey users, we should find a way to proceed even
+      // if we don't know who the author is.
       return;
     }
 
+    $commit_names = self::findRevertedCommits($message);
+    if ($commit_names) {
+      $reverts = id(new DiffusionCommitQuery())
+        ->setViewer($user)
+        ->withIdentifiers($commit_names)
+        ->withDefaultRepository($repository)
+        ->execute();
+      foreach ($reverts as $revert) {
+        // TODO: Do interesting things here.
+      }
+    }
+
     $tasks_statuses = $this->findMentionedTasks($message);
     if (!$tasks_statuses) {
       return;
diff --git a/src/applications/diffusion/query/DiffusionCommitQuery.php b/src/applications/diffusion/query/DiffusionCommitQuery.php
index 789aeb1f59..c9f757aee8 100644
--- a/src/applications/diffusion/query/DiffusionCommitQuery.php
+++ b/src/applications/diffusion/query/DiffusionCommitQuery.php
@@ -5,6 +5,7 @@ final class DiffusionCommitQuery
 
   private $identifiers;
   private $phids;
+  private $defaultRepository;
 
   /**
    * Load commits by partial or full identifiers, e.g. "rXab82393", "rX1234",
@@ -17,6 +18,20 @@ final class DiffusionCommitQuery
     return $this;
   }
 
+  /**
+   * If a default repository is provided, ambiguous commit identifiers will
+   * be assumed to belong to the default repository.
+   *
+   * For example, "r123" appearing in a commit message in repository X is
+   * likely to be unambiguously "rX123". Normally the reference would be
+   * considered ambiguous, but if you provide a default repository it will
+   * be correctly resolved.
+   */
+  public function withDefaultRepository(PhabricatorRepository $repository) {
+    $this->defaultRepository = $repository;
+    return $this;
+  }
+
   public function withPHIDs(array $phids) {
     $this->phids = $phids;
     return $this;
@@ -75,6 +90,12 @@ final class DiffusionCommitQuery
         $repo = nonempty($matches[1], null);
         $identifier = nonempty($matches[2], null);
 
+        if ($repo === null) {
+          if ($this->defaultRepository) {
+            $repo = $this->defaultRepository->getCallsign();
+          }
+        }
+
         if ($repo === null) {
           if (strlen($identifier) < $min_unqualified) {
             continue;