diff --git a/src/api/converter.ts b/src/api/converter.ts
index 905a3ca3f..15fe96091 100644
--- a/src/api/converter.ts
+++ b/src/api/converter.ts
@@ -596,16 +596,16 @@ function toTreeNodesWhenEdit(nodes: Array<CRDTTreeNode>): Array<PbTreeNodes> {
  * `toRHT` converts the given model to Protobuf format.
  */
 function toRHT(rht: RHT): { [key: string]: PbNodeAttr } {
-  const pbAttrs: { [key: string]: PbNodeAttr } = {};
-  for (const [key, rhtNode] of rht.getNodeMapByKey()) {
-    pbAttrs[key] = new PbNodeAttr({
-      value: rhtNode.getValue(),
-      updatedAt: toTimeTicket(rhtNode.getUpdatedAt()),
-      isRemoved: rhtNode.isRemoved(),
+  const pbRHT: { [key: string]: PbNodeAttr } = {};
+  for (const node of rht) {
+    pbRHT[node.getKey()] = new PbNodeAttr({
+      value: node.getValue(),
+      updatedAt: toTimeTicket(node.getUpdatedAt()),
+      isRemoved: node.isRemoved(),
     });
   }
 
-  return pbAttrs;
+  return pbRHT;
 }
 
 /**