diff --git a/src/events/constant/ArcanistEventType.php b/src/events/constant/ArcanistEventType.php
index 37879396..35a116cc 100644
--- a/src/events/constant/ArcanistEventType.php
+++ b/src/events/constant/ArcanistEventType.php
@@ -20,6 +20,7 @@ final class ArcanistEventType extends PhutilEventType {
 
   const TYPE_COMMIT_WILLCOMMITSVN   = 'commit.willCommitSVN';
   const TYPE_DIFF_WILLBUILDMESSAGE  = 'diff.willBuildMessage';
+  const TYPE_DIFF_DIDBUILDMESSAGE   = 'diff.didBuildMessage';
   const TYPE_DIFF_WASCREATED        = 'diff.wasCreated';
 
 }
diff --git a/src/workflow/ArcanistDiffWorkflow.php b/src/workflow/ArcanistDiffWorkflow.php
index 8a7f1d25..8cc4c60b 100644
--- a/src/workflow/ArcanistDiffWorkflow.php
+++ b/src/workflow/ArcanistDiffWorkflow.php
@@ -383,6 +383,9 @@ EOTEXT
 
     $commit_message = $this->buildCommitMessage();
 
+    PhutilEventEngine::dispatchEvent(
+      new PhutilEvent(ArcanistEventType::TYPE_DIFF_DIDBUILDMESSAGE));
+
     if (!$this->shouldOnlyCreateDiff()) {
       $revision = $this->buildRevisionFromCommitMessage($commit_message);
     }