diff --git a/.github/workflows/php-test.yml b/.github/workflows/php-test.yml
index acf2b37..c51361e 100644
--- a/.github/workflows/php-test.yml
+++ b/.github/workflows/php-test.yml
@@ -19,6 +19,9 @@ jobs:
           - "8.0"
           - "8.1"
           - "8.2"
+          - "8.3"
+          - "8.4"
+          - "8.5"
 
     services:
       memcached:
diff --git a/src/DalResolver.php b/src/DalResolver.php
index c7d4e46..1aaf98b 100644
--- a/src/DalResolver.php
+++ b/src/DalResolver.php
@@ -33,9 +33,9 @@ class DalResolver implements IConnectionResolver
   const MODE_WRITE = 'w';
 
   public function __construct(
-    ConfigProviderInterface $connectionConfig = null,
-    ConfigProviderInterface $datastoreConfig = null,
-    ConfigProviderInterface $dalConfig = null
+    ?ConfigProviderInterface $connectionConfig = null,
+    ?ConfigProviderInterface $datastoreConfig = null,
+    ?ConfigProviderInterface $dalConfig = null
   )
   {
     if($connectionConfig !== null)
diff --git a/src/Exceptions/Connection/CqlException.php b/src/Exceptions/Connection/CqlException.php
index 77a3c5f..47cfb66 100644
--- a/src/Exceptions/Connection/CqlException.php
+++ b/src/Exceptions/Connection/CqlException.php
@@ -12,7 +12,7 @@
 
 class CqlException extends ConnectionException
 {
-  public function __construct($msg = "", $code = 0, \Exception $previous = null)
+  public function __construct($msg = "", $code = 0, ?\Exception $previous = null)
   {
     if($previous !== null)
     {
diff --git a/src/Foundation/AbstractSanitizableDao.php b/src/Foundation/AbstractSanitizableDao.php
index 14c711f..27e2d81 100644
--- a/src/Foundation/AbstractSanitizableDao.php
+++ b/src/Foundation/AbstractSanitizableDao.php
@@ -199,7 +199,7 @@ public function validateDaoProperty(
    * @throws \Exception
    * @throws mixed
    */
-  public function isValid(array $properties = null, $throw = false)
+  public function isValid(?array $properties = null, $throw = false)
   {
     $isValid = true;
     if($properties === null)
diff --git a/src/ISanitizableDao.php b/src/ISanitizableDao.php
index e2f38ff..14bf8f3 100644
--- a/src/ISanitizableDao.php
+++ b/src/ISanitizableDao.php
@@ -48,7 +48,7 @@ public function validateDaoProperty(
    * @throws \Exception
    * @throws mixed
    */
-  public function isValid(array $properties = null, $throw = false);
+  public function isValid(?array $properties = null, $throw = false);
 
   /**
    * Serialize a value based on the rules of a property
diff --git a/src/Ql/AbstractQlConnection.php b/src/Ql/AbstractQlConnection.php
index 3d3bd54..9999447 100644
--- a/src/Ql/AbstractQlConnection.php
+++ b/src/Ql/AbstractQlConnection.php
@@ -122,7 +122,7 @@ public function switchDatabase($db)
     }
   }
 
-  abstract protected function _runQuery($query, array $values = null);
+  abstract protected function _runQuery($query, ?array $values = null);
 
   /**
    * Execute a query
@@ -134,7 +134,7 @@ abstract protected function _runQuery($query, array $values = null);
    *
    * @throws ConnectionException
    */
-  public function runQuery($query, array $values = null)
+  public function runQuery($query, ?array $values = null)
   {
     $perfId = $this->getResolver()->startPerformanceMetric(
       $this,
@@ -155,7 +155,7 @@ function () use ($query) {
     return $result;
   }
 
-  abstract protected function _fetchQueryResults($query, array $values = null);
+  abstract protected function _fetchQueryResults($query, ?array $values = null);
 
   /**
    * Fetch the results of the query
@@ -167,7 +167,7 @@ abstract protected function _fetchQueryResults($query, array $values = null);
    *
    * @throws ConnectionException
    */
-  public function fetchQueryResults($query, array $values = null)
+  public function fetchQueryResults($query, ?array $values = null)
   {
     $perfId = $this->getResolver()->startPerformanceMetric(
       $this,
diff --git a/src/Ql/Cql/CqlConnection.php b/src/Ql/Cql/CqlConnection.php
index fa6f6ed..5e8b0bb 100644
--- a/src/Ql/Cql/CqlConnection.php
+++ b/src/Ql/Cql/CqlConnection.php
@@ -344,7 +344,7 @@ protected function _setKeyspace($keyspace, $force = false)
    * @throws \Exception
    * @throws \Packaged\Dal\Exceptions\DalException
    */
-  public function runQuery($query, array $values = null)
+  public function runQuery($query, ?array $values = null)
   {
     $this->_prepareAndExecute(
       DalResolver::MODE_WRITE,
@@ -366,7 +366,7 @@ public function runQuery($query, array $values = null)
    * @throws \Exception
    * @throws \Packaged\Dal\Exceptions\DalException
    */
-  public function fetchQueryResults($query, array $values = null)
+  public function fetchQueryResults($query, ?array $values = null)
   {
     return $this->_prepareAndExecute(
       DalResolver::MODE_READ,
@@ -387,7 +387,7 @@ public function fetchQueryResults($query, array $values = null)
    * @throws \Exception
    * @throws \Packaged\Dal\Exceptions\DalException
    */
-  protected function _prepareAndExecute($mode, $consistency, $query, array $values = null)
+  protected function _prepareAndExecute($mode, $consistency, $query, ?array $values = null)
   {
     $perfId = $this->getResolver()->startPerformanceMetric($this, $mode, $query);
     if($values)
diff --git a/src/Ql/IQLDataConnection.php b/src/Ql/IQLDataConnection.php
index a71d20b..a71aabc 100644
--- a/src/Ql/IQLDataConnection.php
+++ b/src/Ql/IQLDataConnection.php
@@ -13,7 +13,7 @@ interface IQLDataConnection extends IDataConnection
    *
    * @return int number of affected rows
    */
-  public function runQuery($query, array $values = null);
+  public function runQuery($query, ?array $values = null);
 
   /**
    * Fetch the results of the query
@@ -23,5 +23,5 @@ public function runQuery($query, array $values = null);
    *
    * @return array
    */
-  public function fetchQueryResults($query, array $values = null);
+  public function fetchQueryResults($query, ?array $values = null);
 }
diff --git a/src/Ql/MySQLiConnection.php b/src/Ql/MySQLiConnection.php
index bcb7602..a975cfb 100644
--- a/src/Ql/MySQLiConnection.php
+++ b/src/Ql/MySQLiConnection.php
@@ -185,7 +185,7 @@ protected function _shouldReconnectAfterException(\Exception $e)
       || ($p && in_array((string)$p->getCode(), $codes, true));
   }
 
-  protected function _runQuery($query, array $values = null)
+  protected function _runQuery($query, ?array $values = null)
   {
     $stmt = $this->_executeQuery($query, $values);
     $rows = $stmt->affected_rows;
@@ -193,7 +193,7 @@ protected function _runQuery($query, array $values = null)
     return $rows;
   }
 
-  protected function _fetchQueryResults($query, array $values = null)
+  protected function _fetchQueryResults($query, ?array $values = null)
   {
     $stmt = $this->_executeQuery($query, $values);
     $result = $stmt->get_result();
@@ -208,7 +208,7 @@ protected function _fetchQueryResults($query, array $values = null)
     return $rows;
   }
 
-  private function _executeQuery($query, array $values = null)
+  private function _executeQuery($query, ?array $values = null)
   {
     $stmt = $this->_getStatement($query);
     if($values)
diff --git a/src/Ql/PdoConnection.php b/src/Ql/PdoConnection.php
index 1229371..b34ecc8 100644
--- a/src/Ql/PdoConnection.php
+++ b/src/Ql/PdoConnection.php
@@ -100,7 +100,7 @@ protected function _switchDatabase($db)
     }
   }
 
-  protected function _fetchQueryResults($query, array $values = null)
+  protected function _fetchQueryResults($query, ?array $values = null)
   {
     $stmt = $this->_executeQuery($query, $values);
     $rows = $stmt->fetchAll(\PDO::FETCH_ASSOC);
@@ -108,7 +108,7 @@ protected function _fetchQueryResults($query, array $values = null)
     return $rows;
   }
 
-  protected function _runQuery($query, array $values = null)
+  protected function _runQuery($query, ?array $values = null)
   {
     $stmt = $this->_executeQuery($query, $values);
     $rows = $stmt->rowCount();
@@ -271,7 +271,7 @@ protected function _shouldReconnectAfterException(\Exception $e)
       || ($p && in_array((string)$p->getCode(), $codes, true));
   }
 
-  private function _executeQuery($query, array $values = null)
+  private function _executeQuery($query, ?array $values = null)
   {
     $stmt = $this->_getStatement($query);
     if($values)
diff --git a/tests/Ql/Cql/CqlQueryObserverConnection.php b/tests/Ql/Cql/CqlQueryObserverConnection.php
index 9691e47..a3993ff 100644
--- a/tests/Ql/Cql/CqlQueryObserverConnection.php
+++ b/tests/Ql/Cql/CqlQueryObserverConnection.php
@@ -13,7 +13,7 @@ public function getQueries()
     return $this->_queryLog;
   }
 
-  public function runQuery($query, array $values = null)
+  public function runQuery($query, ?array $values = null)
   {
     $this->_queryLog[] = ['runQuery', $query, $values];
     return parent::runQuery($query, $values);
diff --git a/tests/Ql/Mocks/MockAbstractQlDataConnection.php b/tests/Ql/Mocks/MockAbstractQlDataConnection.php
index 37f4964..4e11f4a 100644
--- a/tests/Ql/Mocks/MockAbstractQlDataConnection.php
+++ b/tests/Ql/Mocks/MockAbstractQlDataConnection.php
@@ -33,14 +33,14 @@ public function getExecutedQueryValues()
     return $this->_values;
   }
 
-  public function runQuery($query, array $values = null)
+  public function runQuery($query, ?array $values = null)
   {
     $this->_query = $query;
     $this->_values = $values;
     return $this->_runResult;
   }
 
-  public function fetchQueryResults($query, array $values = null)
+  public function fetchQueryResults($query, ?array $values = null)
   {
     $this->runQuery($query, $values);
     return $this->_fetchResult;