diff --git a/lib/StripeObject.php b/lib/StripeObject.php
index c256bc9b0..41c066c6f 100644
--- a/lib/StripeObject.php
+++ b/lib/StripeObject.php
@@ -417,7 +417,7 @@ public function toArray()
                 return null;
             }
 
-            return method_exists($value, 'toArray') ? $value->toArray() : $value;
+            return is_object($value) && method_exists($value, 'toArray') ? $value->toArray() : $value;
         };
 
         return array_reduce(array_keys($this->_values), function ($acc, $k) use ($maybeToArray) {