diff --git a/src/Bulk/BulkOperator.php b/src/Bulk/BulkOperator.php
index 6b444a9..500b2cc 100644
--- a/src/Bulk/BulkOperator.php
+++ b/src/Bulk/BulkOperator.php
@@ -11,10 +11,8 @@ abstract class BulkOperator
 {
     /**
      * The PDO connection.
-     *
-     * @var \PDO
      */
-    private $pdo;
+    private \PDO $pdo;
 
     /**
      * The name of the target database table.
@@ -39,10 +37,8 @@ abstract class BulkOperator
 
     /**
      * The number of records to process per query.
-     *
-     * @var int
      */
-    private $operationsPerQuery;
+    private int $operationsPerQuery;
 
     /**
      * The prepared statement to process a full batch of records.
@@ -53,33 +49,25 @@ abstract class BulkOperator
 
     /**
      * A buffer containing the pending values to process in the next batch.
-     *
-     * @var array
      */
-    private $buffer = [];
+    private array $buffer = [];
 
     /**
      * The number of operations in the buffer.
-     *
-     * @var int
      */
-    private $bufferSize = 0;
+    private int $bufferSize = 0;
 
     /**
      * The total number of operations that have been queued.
      *
      * This includes both flushed and pending operations.
-     *
-     * @var int
      */
-    private $totalOperations = 0;
+    private int $totalOperations = 0;
 
     /**
      * The total number of rows affected by flushed operations.
-     *
-     * @var int
      */
-    private $affectedRows = 0;
+    private int $affectedRows = 0;
 
     /**
      * @param \PDO     $pdo                The PDO connection.
diff --git a/tests/Bulk/PDOMock.php b/tests/Bulk/PDOMock.php
index 7dfb270..e7d3bfd 100644
--- a/tests/Bulk/PDOMock.php
+++ b/tests/Bulk/PDOMock.php
@@ -9,22 +9,19 @@
  */
 class PDOMock extends \PDO
 {
-    /**
-     * @var int
-     */
-    private $statementNumber = 0;
+    private int $statementNumber = 0;
 
     /**
      * @var string[]
      */
-    private $log = [];
+    private array $log = [];
 
     /**
      * The values that will be returned by successive calls to PDOStatementMock::rowCount().
      *
      * @var int[]
      */
-    private $rowCounts;
+    private array $rowCounts;
 
     /**
      * @param array $rowCounts The values that will be returned by successive calls to PDOStatementMock::rowCount().
diff --git a/tests/Bulk/PDOStatementMock.php b/tests/Bulk/PDOStatementMock.php
index 2fe5493..727b223 100644
--- a/tests/Bulk/PDOStatementMock.php
+++ b/tests/Bulk/PDOStatementMock.php
@@ -9,15 +9,9 @@
  */
 class PDOStatementMock extends \PDOStatement
 {
-    /**
-     * @var PDOMock
-     */
-    private $pdo;
+    private PDOMock $pdo;
 
-    /**
-     * @var int
-     */
-    private $number;
+    private int $number;
 
     /**
      * @param PDOMock $pdo