diff --git a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldRemarkup.php b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldRemarkup.php
--- a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldRemarkup.php
+++ b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldRemarkup.php
@@ -103,4 +103,8 @@
     return false;
   }
 
+  public function getConduitEditParameterType() {
+    return new ConduitStringParameterType();
+  }
+
 }
diff --git a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldText.php b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldText.php
--- a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldText.php
+++ b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldText.php
@@ -71,4 +71,8 @@
     return false;
   }
 
+  public function getConduitEditParameterType() {
+    return new ConduitStringParameterType();
+  }
+
 }