diff --git a/packages/incremental-merkle-tree.sol/contracts/IncrementalBinaryTree.sol b/packages/incremental-merkle-tree.sol/contracts/IncrementalBinaryTree.sol
index b7455de..5004168 100644
--- a/packages/incremental-merkle-tree.sol/contracts/IncrementalBinaryTree.sol
+++ b/packages/incremental-merkle-tree.sol/contracts/IncrementalBinaryTree.sol
@@ -132,7 +132,7 @@ library IncrementalBinaryTree {
     /// @dev Inserts a leaf in the tree.
     /// @param self: Tree data.
     /// @param leaf: Leaf to be inserted.
-    function insert(IncrementalTreeData storage self, uint256 leaf) public {
+    function insert(IncrementalTreeData storage self, uint256 leaf) public returns (uint256) {
         uint256 depth = self.depth;
 
         require(leaf < SNARK_SCALAR_FIELD, "IncrementalBinaryTree: leaf must be < SNARK_SCALAR_FIELD");
@@ -159,6 +159,7 @@ library IncrementalBinaryTree {
 
         self.root = hash;
         self.numberOfLeaves += 1;
+        return hash;
     }
 
     /// @dev Updates a leaf in the tree.
diff --git a/packages/incremental-merkle-tree.sol/contracts/test/IncrementalBinaryTreeTest.sol b/packages/incremental-merkle-tree.sol/contracts/test/IncrementalBinaryTreeTest.sol
index c97c9cf..8e84640 100644
--- a/packages/incremental-merkle-tree.sol/contracts/test/IncrementalBinaryTreeTest.sol
+++ b/packages/incremental-merkle-tree.sol/contracts/test/IncrementalBinaryTreeTest.sol
@@ -33,9 +33,11 @@ contract IncrementalBinaryTreeTest {
     function insertLeaf(bytes32 _treeId, uint256 _leaf) external {
         require(trees[_treeId].depth != 0, "IncrementalBinaryTreeTest: tree does not exist");
 
-        trees[_treeId].insert(_leaf);
+        uint256 root = trees[_treeId].insert(_leaf);
 
-        emit LeafInserted(_treeId, _leaf, trees[_treeId].root);
+        require(root == trees[_treeId].root, "root mismatch");
+
+        emit LeafInserted(_treeId, _leaf, root);
     }
 
     function updateLeaf(