diff --git a/webapp/src/mutator.ts b/webapp/src/mutator.ts
index bbdb78bb1..b3d813001 100644
--- a/webapp/src/mutator.ts
+++ b/webapp/src/mutator.ts
@@ -645,7 +645,7 @@ class Mutator {
         beforeUndo?: () => Promise<void>,
     ): Promise<[Block[], string]> {
         const rootClient = new OctoClient(octoClient.serverUrl, '0')
-        const blocks = await rootClient.getSubtree(boardId, 3)
+        const blocks = await rootClient.getSubtree(boardId, 3, '0')
         const [newBlocks1, newBoard] = OctoUtils.duplicateBlockTree(blocks, boardId) as [Block[], Board, Record<string, string>]
         const newBlocks = newBlocks1.filter((o) => o.type !== 'comment')
         Utils.log(`duplicateBoard: duplicating ${newBlocks.length} blocks`)
diff --git a/webapp/src/octoClient.ts b/webapp/src/octoClient.ts
index 39747af41..5e3fbddc0 100644
--- a/webapp/src/octoClient.ts
+++ b/webapp/src/octoClient.ts
@@ -166,8 +166,8 @@ class OctoClient {
         return user
     }
 
-    async getSubtree(rootId?: string, levels = 2): Promise<Block[]> {
-        let path = this.workspacePath() + `/blocks/${encodeURIComponent(rootId || '')}/subtree?l=${levels}`
+    async getSubtree(rootId?: string, levels = 2, workspaceID?: string): Promise<Block[]> {
+        let path = this.workspacePath(workspaceID) + `/blocks/${encodeURIComponent(rootId || '')}/subtree?l=${levels}`
         const readToken = this.readToken()
         if (readToken) {
             path += `&read_token=${readToken}`