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 304367de4cf6a1221e117e79e2fdb7660d67300c..0f33e1dae944e6ffabe8276ef1775e9e37f6092b 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
@@ -94,7 +94,7 @@ 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)