diff --git a/lib/internal/Magento/Framework/Data/Collection/AbstractDb.php b/lib/internal/Magento/Framework/Data/Collection/AbstractDb.php
index a36a97d0be7f1..b317fdb8385c7 100644
--- a/lib/internal/Magento/Framework/Data/Collection/AbstractDb.php
+++ b/lib/internal/Magento/Framework/Data/Collection/AbstractDb.php
@@ -629,7 +629,7 @@ public function fetchItem()
     /**
      * Overridden to use _idFieldName by default.
      *
-     * @param null $valueField
+     * @param string|null $valueField
      * @param string $labelField
      * @param array $additional
      * @return array