diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
index 324662e5bda8c2c8b3edeaef33012e5be5f4975e..c210b74e8ae106764afa27ddb3d6406f3a73213b 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
@@ -93,7 +93,7 @@ case class Generate(
 
   override def producedAttributes: AttributeSet = AttributeSet(generatorOutput)
 
-  val qualifiedGeneratorOutput: Seq[Attribute] = qualifier.map { q =>
+  def qualifiedGeneratorOutput: Seq[Attribute] = qualifier.map { q =>
     // prepend the new qualifier to the existed one
     generatorOutput.map(a => a.withQualifier(Some(q)))
   }.getOrElse(generatorOutput)