diff --git a/Serializer/ItemNormalizer.php b/Serializer/ItemNormalizer.php
index e68bda8..c928d56 100644
--- a/Serializer/ItemNormalizer.php
+++ b/Serializer/ItemNormalizer.php
@@ -256,7 +256,7 @@ protected function normalizeRelation(ApiProperty $propertyMetadata, ?object $rel
 
         if (null === $relatedObject || isset($context['api_included'])) {
             if (!$this->serializer instanceof NormalizerInterface) {
-                throw new LogicException(sprintf('The injected serializer must be an instance of "%s".', NormalizerInterface::class));
+                throw new LogicException(\sprintf('The injected serializer must be an instance of "%s".', NormalizerInterface::class));
             }
 
             $normalizedRelatedObject = $this->serializer->normalize($relatedObject, $format, $context);
@@ -422,7 +422,7 @@ private function getPopulatedRelations(object $object, ?string $format, array $c
             // Many to many relationship
             foreach ($attributeValue as $attributeValueElement) {
                 if (!isset($attributeValueElement['data'])) {
-                    throw new UnexpectedValueException(sprintf('The JSON API attribute \'%s\' must contain a "data" key.', $relationshipName));
+                    throw new UnexpectedValueException(\sprintf('The JSON API attribute \'%s\' must contain a "data" key.', $relationshipName));
                 }
                 unset($attributeValueElement['data']['attributes']);
                 $data[$relationshipName]['data'][] = $attributeValueElement['data'];