diff --git a/packages/x-data-grid-premium/src/hooks/features/cellSelection/useGridCellSelection.ts b/packages/x-data-grid-premium/src/hooks/features/cellSelection/useGridCellSelection.ts
index 5c4e3020ba616..d36c314e62923 100644
--- a/packages/x-data-grid-premium/src/hooks/features/cellSelection/useGridCellSelection.ts
+++ b/packages/x-data-grid-premium/src/hooks/features/cellSelection/useGridCellSelection.ts
@@ -146,7 +146,7 @@ export const useGridCellSelection = (
       const rowsInRange = visibleRows.rows.slice(finalStartRowIndex, finalEndRowIndex + 1);
       const columnsInRange = visibleColumns.slice(finalStartColumnIndex, finalEndColumnIndex + 1);
 
-      const newModel = keepOtherSelected ? apiRef.current.getCellSelectionModel() : {};
+      const newModel = keepOtherSelected ? { ...apiRef.current.getCellSelectionModel() } : {};
 
       rowsInRange.forEach((row) => {
         if (!newModel[row.id]) {