diff --git a/packages/group/src/group.ts b/packages/group/src/group.ts
index 95962d3a7..75534db2b 100644
--- a/packages/group/src/group.ts
+++ b/packages/group/src/group.ts
@@ -20,7 +20,7 @@ export default class Group {
         }
 
         this._id = id
-        this.merkleTree = new IncrementalMerkleTree(poseidon2, treeDepth, hash(id), 2, members)
+        this.merkleTree = new IncrementalMerkleTree(poseidon2, treeDepth, hash(id), 2, members.map(BigInt))
     }
 
     /**