diff --git a/src/Mapper.php b/src/Mapper.php
index 6cb920d..e615619 100644
--- a/src/Mapper.php
+++ b/src/Mapper.php
@@ -405,7 +405,7 @@ public function mapToSalesforceObject($model)
 
         /** @var Result\DescribeSObjectResult $objectDescription */
         $objectDescription = $this->getObjectDescription($model);
-        $reflClass = new ReflectionClass((new Configuration())->getClassNameInflector()->getUserClassName($model));
+        $reflClass = new ReflectionClass((new Configuration())->getClassNameInflector()->getUserClassName($model::class));
         $mappedProperties = $this->annotationReader->getSalesforceFields($model);
         $mappedRelations = $this->annotationReader->getSalesforceRelations($model);
         $allMappings = $mappedProperties->toArray() + $mappedRelations;