diff --git a/tree/arbo/proof.go b/tree/arbo/proof.go
index 947cbfa66..35fc110ce 100644
--- a/tree/arbo/proof.go
+++ b/tree/arbo/proof.go
@@ -247,6 +247,8 @@ func CalculateProofNodes(hashFunc HashFunction, k, v, packedSiblings, oldKey []b
 // CheckProofBatch verifies a batch of N proofs pairs (old and new). The proof verification depends on the
 // HashFunction passed as parameter.
 // Returns nil if the batch is valid, or an error otherwise.
+//
+// TODO: doesn't support removing leaves (newProofs can only update or add new leaves)
 func CheckProofBatch(hashFunc HashFunction, oldProofs, newProofs []*CircomVerifierProof) error {
 	newBranches := make(map[string]int)
 	newSiblings := make(map[string]int)