diff --git a/spark/src/main/scala/io/substrait/spark/logical/ToSubstraitRel.scala b/spark/src/main/scala/io/substrait/spark/logical/ToSubstraitRel.scala
index 3ba86c7a2..695f93919 100644
--- a/spark/src/main/scala/io/substrait/spark/logical/ToSubstraitRel.scala
+++ b/spark/src/main/scala/io/substrait/spark/logical/ToSubstraitRel.scala
@@ -145,7 +145,7 @@ class ToSubstraitRel extends AbstractLogicalPlanVisitor with Logging {
     }
     val groupOutputMap = actualGroupExprs.zipWithIndex.map {
       case (e, i) =>
-        AttributeReference(s"group_col_$i", e.dataType)() -> e
+        AttributeReference(s"group_col_$i", e.dataType, nullable = e.nullable)() -> e
     }
     val groupOutput = groupOutputMap.map(_._1)