diff --git a/src/Illuminate/Testing/Constraints/HasInDatabase.php b/src/Illuminate/Testing/Constraints/HasInDatabase.php
index e687ec7cc625..2e196943369c 100644
--- a/src/Illuminate/Testing/Constraints/HasInDatabase.php
+++ b/src/Illuminate/Testing/Constraints/HasInDatabase.php
@@ -113,7 +113,7 @@ protected function getAdditionalInfo($table)
     public function toString($options = 0)/*: string*/
     {
         foreach ($this->data as $key => $data) {
-            $output[$key] = $data instanceof Expression ? (string) $data : $data;
+            $output[$key] = $data instanceof Expression ? $data->getValue($this->database->getQueryGrammar()) : $data;
         }
 
         return json_encode(isset($output) ? $output : [], $options);