diff --git a/src/Illuminate/Validation/Concerns/ValidatesAttributes.php b/src/Illuminate/Validation/Concerns/ValidatesAttributes.php
index d62ec0ee9513..84e0964ba147 100644
--- a/src/Illuminate/Validation/Concerns/ValidatesAttributes.php
+++ b/src/Illuminate/Validation/Concerns/ValidatesAttributes.php
@@ -1164,7 +1164,7 @@ public function validateJson($attribute, $value)
             return false;
         }
 
-        if (! is_scalar($value) && ! method_exists($value, '__toString')) {
+        if (! is_scalar($value) && ! is_null($value) && ! method_exists($value, '__toString')) {
             return false;
         }