diff --git a/lib/querybuilder/Model/AbstractQueryBuilderOperator.php b/lib/querybuilder/Model/AbstractQueryBuilderOperator.php
index e01efab53..2928da305 100644
--- a/lib/querybuilder/Model/AbstractQueryBuilderOperator.php
+++ b/lib/querybuilder/Model/AbstractQueryBuilderOperator.php
@@ -27,7 +27,7 @@ abstract class AbstractQueryBuilderOperator implements QueryBuilderOperatorInter
     /**
      * Operator.
      *
-     * @var string
+     * @var string|null
      */
     private $operator;
 
diff --git a/lib/querybuilder/Model/QueryBuilderValidation.php b/lib/querybuilder/Model/QueryBuilderValidation.php
index cc922f5b4..0536582c4 100644
--- a/lib/querybuilder/Model/QueryBuilderValidation.php
+++ b/lib/querybuilder/Model/QueryBuilderValidation.php
@@ -61,14 +61,14 @@ class QueryBuilderValidation implements QueryBuilderValidationInterface {
     /**
      * Min.
      *
-     * @var mixed
+     * @var mixed|null
      */
     private $min;
 
     /**
      * Step.
      *
-     * @var mixed
+     * @var mixed|null
      */
     private $step;