diff --git a/core/lib/Drupal/Core/Database/Query/Condition.php b/core/lib/Drupal/Core/Database/Query/Condition.php
index 9faabc6..f7d2a2f 100644
--- a/core/lib/Drupal/Core/Database/Query/Condition.php
+++ b/core/lib/Drupal/Core/Database/Query/Condition.php
@@ -260,7 +260,7 @@ class Condition implements ConditionInterface, Countable {
   function __clone() {
     $this->changed = TRUE;
     foreach ($this->conditions as $key => $condition) {
-      if ($condition['field'] instanceOf ConditionInterface) {
+      if ($key !== '#conjunction' && $condition['field'] instanceOf ConditionInterface) {
         $this->conditions[$key]['field'] = clone($condition['field']);
       }
     }