diff --git a/packages/lean-imt/src/lean-imt.ts b/packages/lean-imt/src/lean-imt.ts
index d4cbcb6b9..4fdc4f067 100644
--- a/packages/lean-imt/src/lean-imt.ts
+++ b/packages/lean-imt/src/lean-imt.ts
@@ -238,25 +238,21 @@ export default class LeanIMT<N = bigint> {
      * It is more efficient than using the {@link LeanIMT#update} method N times because it
      * prevents updating middle nodes several times. This would happen when updating leaves
      * with common ancestors.
-     * @param leaves The list of leaves to be updated.
      * @param indices The list of indices of the respective leaves.
+     * @param leaves The list of leaves to be updated.
      */
-    public updateMany(leaves: N[], indices: number[]) {
+    public updateMany(indices: number[], leaves: N[]) {
         requireDefined(leaves, "leaves")
         requireDefined(indices, "indices")
         requireArray(leaves, "leaves")
         requireArray(indices, "indices")
 
-        if (leaves.length === 0) {
-            throw new Error("There are no leaves to modify")
-        }
         if (leaves.length !== indices.length) {
             throw new Error("There is no correspondence between indices and leaves")
         }
         for (let leaf = 0; leaf < indices.length; leaf += 1) {
             if (indices[leaf] < 0 || indices[leaf] >= this.size) {
                 throw new Error(`Index ${leaf} is out of range`)
-                // throw new Error("Index " + leaf.toString() + " is out of range")
             }
         }
 
diff --git a/packages/lean-imt/tests/lean-imt.test.ts b/packages/lean-imt/tests/lean-imt.test.ts
index 0fb3c57e6..1c7633cd0 100644
--- a/packages/lean-imt/tests/lean-imt.test.ts
+++ b/packages/lean-imt/tests/lean-imt.test.ts
@@ -220,6 +220,59 @@ describe("Lean IMT", () => {
         })
     })
 
+    describe("# updateMany", () => {
+        it(`Should not update any leaf if one of the parameters is not defined`, () => {
+            const tree = new LeanIMT(poseidon, leaves)
+
+            const fun1 = () => tree.updateMany([1], undefined as any)
+            const fun2 = () => tree.updateMany(undefined as any, [BigInt(1)])
+
+            expect(fun1).toThrow("Parameter 'leaves' is not defined")
+            expect(fun2).toThrow("Parameter 'indices' is not defined")
+        })
+
+        it(`Should not update any leaf if the parameters are not arrays`, () => {
+            const tree = new LeanIMT(poseidon, leaves)
+
+            const fun1 = () => tree.updateMany([3], BigInt(1) as any)
+            const fun2 = () => tree.updateMany(3 as any, [BigInt(1)])
+
+            expect(fun1).toThrow("Parameter 'leaves' is not an Array instance")
+            expect(fun2).toThrow("Parameter 'indices' is not an Array instance")
+        })
+
+        it(`Should not update any leaf if the parameters are of different size`, () => {
+            const tree = new LeanIMT(poseidon, leaves)
+
+            const fun = () => tree.updateMany([1, 2, 3], [BigInt(1), BigInt(2)])
+
+            expect(fun).toThrow("There is no correspondence between indices and leaves")
+        })
+
+        it(`Should not update any leaf if some index is out of range`, () => {
+            const tree = new LeanIMT(poseidon, leaves)
+
+            const fun1 = () => tree.updateMany([-1, 2, 3], [BigInt(1), BigInt(2), BigInt(3)])
+            const fun2 = () => tree.updateMany([1, 200000, 3], [BigInt(1), BigInt(2), BigInt(3)])
+            const fun3 = () => tree.updateMany([1, 2, 345], [BigInt(1), BigInt(2), BigInt(3)])
+
+            expect(fun1).toThrow("Index 0 is out of range")
+            expect(fun2).toThrow("Index 1 is out of range")
+            expect(fun3).toThrow("Index 2 is out of range")
+        })
+
+        it(`Should not update any leaf when passing an empty list`, () => {
+            const tree = new LeanIMT(poseidon, leaves)
+            const previousRoot = tree.root
+
+            tree.updateMany([], [])
+
+            expect(tree.root).toBe(previousRoot)
+        })
+
+        it(`Should update leafs correctly`, () => {})
+    })
+
     describe("# generateProof", () => {
         it(`Should not generate any proof if the index is not defined`, () => {
             const tree = new LeanIMT(poseidon, leaves)