diff --git a/src/Header/Header.tsx b/src/Header/Header.tsx
index a3aa05bb1..7833051e9 100644
--- a/src/Header/Header.tsx
+++ b/src/Header/Header.tsx
@@ -1,5 +1,12 @@
 import * as React from 'react';
-import { ColumnsType, CellType, StickyOffsets, ColumnType, GetComponentProps } from '../interface';
+import {
+  ColumnsType,
+  CellType,
+  StickyOffsets,
+  ColumnType,
+  GetComponentProps,
+  ColumnGroupType,
+} from '../interface';
 import HeaderRow from './HeaderRow';
 import TableContext from '../context/TableContext';
 
@@ -28,11 +35,12 @@ function parseHeaderRows<RecordType>(
 
       let colSpan: number = 1;
 
-      if ('children' in column) {
-        colSpan = fillRowCells(column.children, currentColIndex, rowIndex + 1).reduce(
-          (total, count) => total + count,
-          0,
-        );
+      if ((column as ColumnGroupType<RecordType>).children) {
+        colSpan = fillRowCells(
+          (column as ColumnGroupType<RecordType>).children,
+          currentColIndex,
+          rowIndex + 1,
+        ).reduce((total, count) => total + count, 0);
         cell.hasSubColumns = true;
       }
 
diff --git a/src/hooks/useColumns.tsx b/src/hooks/useColumns.tsx
index 3d527c45b..8b8f37e06 100644
--- a/src/hooks/useColumns.tsx
+++ b/src/hooks/useColumns.tsx
@@ -9,6 +9,7 @@ import {
   GetRowKey,
   TriggerEventHandler,
   RenderExpandIcon,
+  ColumnGroupType,
 } from '../interface';
 import { INTERNAL_COL_DEFINE } from '../utils/legacyUtil';
 
@@ -39,10 +40,10 @@ function flatColumns<RecordType>(columns: ColumnsType<RecordType>): ColumnType<R
     // Convert `fixed='true'` to `fixed='left'` instead
     const parsedFixed = fixed === true ? 'left' : fixed;
 
-    if ('children' in column) {
+    if ((column as ColumnGroupType<RecordType>).children) {
       return [
         ...list,
-        ...flatColumns(column.children).map(subColum => ({
+        ...flatColumns((column as ColumnGroupType<RecordType>).children).map(subColum => ({
           fixed: parsedFixed,
           ...subColum,
         })),