diff --git a/lib/Doctrine/DBAL/Query/QueryBuilder.php b/lib/Doctrine/DBAL/Query/QueryBuilder.php
index 46d7db7a21e..587e26656ab 100644
--- a/lib/Doctrine/DBAL/Query/QueryBuilder.php
+++ b/lib/Doctrine/DBAL/Query/QueryBuilder.php
@@ -52,23 +52,28 @@ class QueryBuilder
      */
     private $connection;
 
+    /*
+     * The default values of SQL parts collection
+     */
+    private const SQL_PARTS_DEFAULTS = [
+        'select'   => [],
+        'distinct' => false,
+        'from'     => [],
+        'join'     => [],
+        'set'      => [],
+        'where'    => null,
+        'groupBy'  => [],
+        'having'   => null,
+        'orderBy'  => [],
+        'values'   => [],
+    ];
+
     /**
      * The array of SQL parts collected.
      *
      * @var mixed[]
      */
-    private $sqlParts = [
-        'select'  => [],
-        'distinct'  => false,
-        'from'    => [],
-        'join'    => [],
-        'set'     => [],
-        'where'   => null,
-        'groupBy' => [],
-        'having'  => null,
-        'orderBy' => [],
-        'values'  => [],
-    ];
+    private $sqlParts = self::SQL_PARTS_DEFAULTS;
 
     /**
      * The complete SQL string for this query.
@@ -1103,8 +1108,7 @@ public function resetQueryParts($queryPartNames = null)
      */
     public function resetQueryPart($queryPartName)
     {
-        $this->sqlParts[$queryPartName] = is_array($this->sqlParts[$queryPartName])
-            ? [] : null;
+        $this->sqlParts[$queryPartName] = self::SQL_PARTS_DEFAULTS[$queryPartName];
 
         $this->state = self::STATE_DIRTY;