diff --git a/app/code/Magento/ConfigurableProduct/Model/Product/Type/Configurable.php b/app/code/Magento/ConfigurableProduct/Model/Product/Type/Configurable.php
index 47c1a3c39f9a8..a849d964eaed5 100644
--- a/app/code/Magento/ConfigurableProduct/Model/Product/Type/Configurable.php
+++ b/app/code/Magento/ConfigurableProduct/Model/Product/Type/Configurable.php
@@ -1249,7 +1249,7 @@ public function getUsedProducts($product, $requiredAttributeIds = null)
             $product->getStoreId(),
             $this->getCustomerSession()->getCustomerGroupId()
         ];
-        if (!is_null($requiredAttributeIds)) {
+        if ($requiredAttributeIds !== null) {
             sort($requiredAttributeIds);
             $keyParts[] = implode('', $requiredAttributeIds);
         }