diff --git a/src/applications/calendar/xaction/PhabricatorCalendarEventDescriptionTransaction.php b/src/applications/calendar/xaction/PhabricatorCalendarEventDescriptionTransaction.php
--- a/src/applications/calendar/xaction/PhabricatorCalendarEventDescriptionTransaction.php
+++ b/src/applications/calendar/xaction/PhabricatorCalendarEventDescriptionTransaction.php
@@ -39,4 +39,15 @@
       ->setNewText($this->getNewValue());
   }
 
+  public function newRemarkupChanges() {
+    $changes = array();
+
+    $changes[] = $this->newRemarkupChange()
+      ->setOldValue($this->getOldValue())
+      ->setNewValue($this->getNewValue());
+
+    return $changes;
+  }
+
+
 }
diff --git a/src/applications/transactions/storage/PhabricatorModularTransaction.php b/src/applications/transactions/storage/PhabricatorModularTransaction.php
--- a/src/applications/transactions/storage/PhabricatorModularTransaction.php
+++ b/src/applications/transactions/storage/PhabricatorModularTransaction.php
@@ -149,4 +149,8 @@
     return parent::renderChangeDetails($viewer);
   }
 
+  final protected function newRemarkupChanges() {
+    return $this->getTransactionImplementation()->newRemarkupChanges();
+  }
+
 }
diff --git a/src/applications/transactions/storage/PhabricatorModularTransactionType.php b/src/applications/transactions/storage/PhabricatorModularTransactionType.php
--- a/src/applications/transactions/storage/PhabricatorModularTransactionType.php
+++ b/src/applications/transactions/storage/PhabricatorModularTransactionType.php
@@ -67,6 +67,10 @@
     throw new PhutilMethodNotImplementedException();
   }
 
+  public function newRemarkupChanges() {
+    return array();
+  }
+
   final public function setStorage(
     PhabricatorApplicationTransaction $xaction) {
     $this->storage = $xaction;
@@ -253,4 +257,9 @@
     return ($target == PhabricatorApplicationTransaction::TARGET_TEXT);
   }
 
+  final protected function newRemarkupChange() {
+    return id(new PhabricatorTransactionRemarkupChange())
+      ->setTransaction($this->getStorage());
+  }
+
 }