diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/UserDefinedType.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/UserDefinedType.scala
index fb7251d71b9b..bd523ef7c361 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/UserDefinedType.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/UserDefinedType.scala
@@ -95,6 +95,7 @@ abstract class UserDefinedType[UserType >: Null] extends DataType with Serializa
  *
  * Note: This can only be accessed via Python UDF, or accessed as serialized object.
  */
+@DeveloperApi
 private[sql] class PythonUserDefinedType(
     val sqlType: DataType,
     override val pyUDT: String,