diff --git a/framework/db/QueryBuilder.php b/framework/db/QueryBuilder.php
index bb8f4dbc3b..e31685eeb2 100644
--- a/framework/db/QueryBuilder.php
+++ b/framework/db/QueryBuilder.php
@@ -1202,6 +1202,7 @@ class QueryBuilder extends \yii\base\Object
      * @param array $operands contains two column names.
      * @param array $params the binding parameters to be populated
      * @return string the generated SQL expression
+     * @throws InvalidParamException if wrong number of operands have been given.
      */
     public function buildSimpleCondition($operator, $operands, &$params)
     {