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 1c255861ad3af..a0086c1504bae 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
@@ -378,7 +378,7 @@ case class AppendData(
           case (inAttr, outAttr) =>
             // names and types must match, nullability must be compatible
             inAttr.name == outAttr.name &&
-                DataType.equalsIgnoreCompatibleNullability(outAttr.dataType, inAttr.dataType) &&
+                DataType.equalsIgnoreCompatibleNullability(inAttr.dataType, outAttr.dataType) &&
                 (outAttr.nullable || !inAttr.nullable)
         }
   }