diff --git a/src/workflow/ArcanistDiffWorkflow.php b/src/workflow/ArcanistDiffWorkflow.php
--- a/src/workflow/ArcanistDiffWorkflow.php
+++ b/src/workflow/ArcanistDiffWorkflow.php
@@ -587,17 +587,20 @@
           'differential.createrevision',
           $revision);
 
-        $revised_message = $conduit->callMethodSynchronous(
-          'differential.getcommitmessage',
-          array(
-            'revision_id' => $result['revisionid'],
-          ));
-
         if ($this->shouldAmend()) {
           $repository_api = $this->getRepositoryAPI();
           if ($repository_api->supportsAmend()) {
             echo pht('Updating commit message...')."\n";
+            $revised_message = $conduit->callMethodSynchronous(
+              'differential.getcommitmessage',
+              array(
+                'revision_id' => $result['revisionid'],
+              ));
             $repository_api->amendCommit($revised_message);
+
+            // The above updates the commit object; update the record on
+            // the diff.
+            $this->updateLocalDiffProperty();
           } else {
             echo pht(
               'Commit message was not amended. Amending commit message is '.