diff --git a/library/think/Model.php b/library/think/Model.php
index 7420d563..94b61bac 100644
--- a/library/think/Model.php
+++ b/library/think/Model.php
@@ -1132,7 +1132,7 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
     public function getChangedData()
     {
         $data = array_udiff_assoc($this->data, $this->origin, function ($a, $b) {
-            if ((empty($b) || empty($b)) && $a !== $b) {
+            if ((empty($a) || empty($b)) && $a !== $b) {
                 return 1;
             }
             return is_object($a) || $a != $b ? 1 : 0;