diff --git a/consensus/state.go b/consensus/state.go
index 8ad8a174..62d544ee 100644
--- a/consensus/state.go
+++ b/consensus/state.go
@@ -507,8 +507,8 @@ func (s State) Commitment(txnsHash types.Hash256, minerAddr types.Address) types
 
 // InputSigHash returns the hash that must be signed for each v2 transaction input.
 func (s State) InputSigHash(txn types.V2Transaction) types.Hash256 {
-	// NOTE: This currently covers exactly the same fields as txn.ID(), and for
-	// similar reasons.
+	// NOTE: This currently covers exactly the same fields as txn.ID(), for the
+	// same reasons.
 	h := hasherPool.Get().(*types.Hasher)
 	defer hasherPool.Put(h)
 	h.Reset()
diff --git a/types/hash.go b/types/hash.go
index 258725c2..c8b2a958 100644
--- a/types/hash.go
+++ b/types/hash.go
@@ -15,8 +15,9 @@ func HashBytes(b []byte) Hash256 {
 
 // A Hasher streams objects into an instance of Sia's hash function.
 type Hasher struct {
-	h hash.Hash
-	E *Encoder
+	h   hash.Hash
+	sum Hash256 // prevent Sum from allocating
+	E   *Encoder
 }
 
 // Reset resets the underlying hash and encoder state.
@@ -33,15 +34,15 @@ func (h *Hasher) WriteDistinguisher(p string) {
 // Sum returns the digest of the objects written to the Hasher.
 func (h *Hasher) Sum() (sum Hash256) {
 	_ = h.E.Flush() // no error possible
-	h.h.Sum(sum[:0])
-	return
+	h.h.Sum(h.sum[:0])
+	return h.sum
 }
 
 // NewHasher returns a new Hasher instance.
 func NewHasher() *Hasher {
 	h := blake2b.New256()
 	e := NewEncoder(h)
-	return &Hasher{h, e}
+	return &Hasher{h: h, E: e}
 }
 
 // Pool for reducing heap allocations when hashing. This is only necessary
diff --git a/types/multiproof_test.go b/types/multiproof_test.go
index 464ce426..700dff1f 100644
--- a/types/multiproof_test.go
+++ b/types/multiproof_test.go
@@ -113,9 +113,6 @@ func TestMultiproofEncoding(t *testing.T) {
 			t.Fatal(err)
 		}
 		if !reflect.DeepEqual(b, b2) {
-			t.Log(b.Transactions[0].SiacoinInputs[0].Parent.MerkleProof)
-			t.Log(b2.Transactions[0].SiacoinInputs[0].Parent.MerkleProof)
-			t.FailNow()
 			t.Fatalf("multiproof encoding of %v txns did not survive roundtrip: expected %v, got %v", n, b, b2)
 		}
 	}
diff --git a/types/types.go b/types/types.go
index 7ca8940a..029bd632 100644
--- a/types/types.go
+++ b/types/types.go
@@ -712,15 +712,6 @@ type V2Transaction struct {
 //
 // To hash all of the data in a transaction, use the FullHash method.
 func (txn *V2Transaction) ID() TransactionID {
-	// NOTE: In general, it is not possible to change a transaction's ID without
-	// causing it to become invalid, but an exception exists for non-standard
-	// spend policies. Consider a policy that may be satisfied by either a
-	// signature or a timelock. If a transaction is broadcast that signs the
-	// input, and the timelock has expired, then anyone may remove the signature
-	// from the input without invalidating the transaction. Of course, the net
-	// result will be the same, so arguably there's little reason to care. You
-	// only need to worry about this if you're hashing the full transaction data
-	// for some reason.
 	h := hasherPool.Get().(*Hasher)
 	defer hasherPool.Put(h)
 	h.Reset()
@@ -753,6 +744,12 @@ func (txn *V2Transaction) ID() TransactionID {
 	h.E.WritePrefix(len(txn.FileContractResolutions))
 	for _, fcr := range txn.FileContractResolutions {
 		fcr.Parent.ID.EncodeTo(h.E)
+		// normalize proof
+		if sp, ok := fcr.Resolution.(*V2StorageProof); ok {
+			c := *sp // don't modify original
+			c.ProofIndex.MerkleProof = nil
+			fcr.Resolution = &c
+		}
 		fcr.Resolution.(EncoderTo).EncodeTo(h.E)
 	}
 	h.E.WritePrefix(len(txn.Attestations))