diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
index 79937b129aeae..75e54944dd118 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
@@ -340,7 +340,7 @@ case class ApproxCountDistinctMergeFunction(
     hyperLogLog.addAll(evaluatedExpr.asInstanceOf[HyperLogLog])
   }
 
-  override def eval(input: Row): Any = hyperLogLog.cardinality()
+  override def eval(input: Row): Any = hyperLogLog.cardinality().toInt
 }
 
 case class SumFunction(expr: Expression, base: AggregateExpression) extends AggregateFunction {