diff --git rules/includes/rules.core.inc rules/includes/rules.core.inc
index 2af6d13..dfbc1ec 100644
--- rules/includes/rules.core.inc
+++ rules/includes/rules.core.inc
@@ -1609,7 +1609,14 @@ abstract class RulesConditionContainer extends RulesContainerPlugin implements R
   }
 
   public function __sleep() {
-    return parent::__sleep() + array('negate' => 'negate');
+    $properties = parent::__sleep();
+    $properties['negate'] = 'negate';
+
+    if (isset($this->label)) {
+      $properties['label'] = 'label';
+    }
+
+    return $properties;
   }
 
   /**