diff --git a/library/think/Model.php b/library/think/Model.php
index 1a9696b6..276f4770 100644
--- a/library/think/Model.php
+++ b/library/think/Model.php
@@ -667,6 +667,10 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
             if (!empty($where)) {
                 $pk = $this->getPk();
                 if (is_string($pk) && isset($data[$pk])) {
+                    if (!isset($where[$pk])) {
+                        unset($where);
+                        $where[$pk] = $data[$pk];
+                    }
                     unset($data[$pk]);
                 }
             }