diff --git a/src/DataDifferencer.php b/src/DataDifferencer.php
index b216cc31..771a2ee6 100644
--- a/src/DataDifferencer.php
+++ b/src/DataDifferencer.php
@@ -59,7 +59,7 @@ class DataDifferencer extends ModelData
      * @param DataObject $fromRecord
      * @param DataObject $toRecord
      */
-    public function __construct(DataObject $fromRecord = null, DataObject $toRecord = null)
+    public function __construct(?DataObject $fromRecord = null, ?DataObject $toRecord = null)
     {
         $this->fromRecord = $fromRecord;
         $this->toRecord = $toRecord;
diff --git a/src/Versioned.php b/src/Versioned.php
index f4e56f9e..e4701c59 100644
--- a/src/Versioned.php
+++ b/src/Versioned.php
@@ -454,7 +454,7 @@ protected function updateInheritableQueryParams(&$params)
      * @param DataQuery|null $dataQuery
      * @throws InvalidArgumentException
      */
-    protected function augmentSQL(SQLSelect $query, DataQuery $dataQuery = null)
+    protected function augmentSQL(SQLSelect $query, ?DataQuery $dataQuery = null)
     {
         if (!$dataQuery) {
             return;
@@ -895,7 +895,7 @@ protected function isTableVersioned($table)
      * @param DataQuery $dataQuery
      * @param DataObject $dataObject
      */
-    protected function augmentLoadLazyFields(SQLSelect &$query, DataQuery &$dataQuery = null, $dataObject)
+    protected function augmentLoadLazyFields(SQLSelect &$query, ?DataQuery &$dataQuery, $dataObject)
     {
         // The VersionedMode local variable ensures that this decorator only applies to
         // queries that have originated from the Versioned object, and have the Versioned