diff --git a/go.mod b/go.mod
index 1c11c15..d15ebd0 100644
--- a/go.mod
+++ b/go.mod
@@ -3,6 +3,7 @@ module github.com/transparency-dev/incubator
 go 1.25.0
 
 require (
+	filippo.io/torchwood v0.9.1-0.20260708154658-e0a6396dd50c
 	github.com/cockroachdb/pebble v1.1.5
 	github.com/go-git/go-git/v5 v5.19.1
 	github.com/google/go-cmp v0.7.0
@@ -18,7 +19,6 @@ require (
 	golang.org/x/mod v0.38.0
 	golang.org/x/sync v0.22.0
 	k8s.io/klog/v2 v2.140.0
-	rsc.io/tmp/mpt v0.2.0
 )
 
 require (
@@ -61,7 +61,7 @@ require (
 	github.com/prometheus/common v0.67.5 // indirect
 	github.com/prometheus/otlptranslator v1.0.0 // indirect
 	github.com/prometheus/procfs v0.20.1 // indirect
-	github.com/rogpeppe/go-internal v1.14.1 // indirect
+	github.com/rogpeppe/go-internal v1.15.0 // indirect
 	github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3 // indirect
 	github.com/skeema/knownhosts v1.3.1 // indirect
 	github.com/xanzy/ssh-agent v0.3.3 // indirect
@@ -69,11 +69,11 @@ require (
 	go.opentelemetry.io/otel/sdk v1.44.0 // indirect
 	go.opentelemetry.io/otel/trace v1.44.0 // indirect
 	go.yaml.in/yaml/v2 v2.4.4 // indirect
-	golang.org/x/crypto v0.52.0 // indirect
-	golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f // indirect
+	golang.org/x/crypto v0.53.0 // indirect
+	golang.org/x/exp v0.0.0-20260603202125-055de637280b // indirect
 	golang.org/x/net v0.55.0 // indirect
-	golang.org/x/sys v0.45.0 // indirect
-	golang.org/x/text v0.37.0 // indirect
+	golang.org/x/sys v0.46.0 // indirect
+	golang.org/x/text v0.38.0 // indirect
 	google.golang.org/protobuf v1.36.11 // indirect
 	gopkg.in/warnings.v0 v0.1.2 // indirect
 )
diff --git a/go.sum b/go.sum
index 97e3429..96ee30e 100644
--- a/go.sum
+++ b/go.sum
@@ -2,6 +2,8 @@ dario.cat/mergo v1.0.0 h1:AGCNq9Evsj31mOgNPcLyXc+4PNABt905YmuqPYYpBWk=
 dario.cat/mergo v1.0.0/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
 filippo.io/mldsa v0.0.0-20260215214346-43d0283efc3e h1:VsUbObBMxXlc23Eb9VeeJYE4jvTs87qa5RqSN2U5FJU=
 filippo.io/mldsa v0.0.0-20260215214346-43d0283efc3e/go.mod h1:32qQ5yj3R24Eu03iWFWchdC3OB653wPvoepWejkefbY=
+filippo.io/torchwood v0.9.1-0.20260708154658-e0a6396dd50c h1:t259W9JzlCso86LB0V92ZmRJluFg1wEsiH4OonKAB5U=
+filippo.io/torchwood v0.9.1-0.20260708154658-e0a6396dd50c/go.mod h1:kKEN0olmFcNGfsPWT3M46wig9CUz7/vHIAENPh9pLXc=
 github.com/DataDog/zstd v1.4.5 h1:EndNeuB0l9syBZhut0wns3gV1hL8zX8LIu6ZiVHWLIQ=
 github.com/DataDog/zstd v1.4.5/go.mod h1:1jcaCB/ufaK+sKp1NBhlGmpz41jOoPQ35bpF36t7BBo=
 github.com/Microsoft/go-winio v0.5.2/go.mod h1:WpS1mjBmmwHBEWmogvA2mj8546UReBk4v8QkMxJ6pZY=
@@ -121,8 +123,8 @@ github.com/prometheus/otlptranslator v1.0.0/go.mod h1:vRYWnXvI6aWGpsdY/mOT/cbeVR
 github.com/prometheus/procfs v0.20.1 h1:XwbrGOIplXW/AU3YhIhLODXMJYyC1isLFfYCsTEycfc=
 github.com/prometheus/procfs v0.20.1/go.mod h1:o9EMBZGRyvDrSPH1RqdxhojkuXstoe4UlK79eF5TGGo=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
-github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
-github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
+github.com/rogpeppe/go-internal v1.15.0 h1:D0RCU5rMAp+SpgkiNdrjfJ+LX4J1M32V2NeCY7EJ6hc=
+github.com/rogpeppe/go-internal v1.15.0/go.mod h1:DrUVZyrJU+txYW5/1kwtXQSMFio52ZOxX7yM1VHvnxs=
 github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3 h1:n661drycOFuPLCN3Uc8sB6B/s6Z4t2xvBgU1htSHuq8=
 github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3/go.mod h1:A0bzQcvG0E7Rwjx0REVgAGH58e96+X0MeOfepqsbeW4=
 github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
@@ -167,10 +169,10 @@ golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACk
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
-golang.org/x/crypto v0.52.0 h1:RMs7fP2rXdep0CftQlK8Uf+kibLm7qkCcradZWYz988=
-golang.org/x/crypto v0.52.0/go.mod h1:1QgfPxDqh0T2M/elOJtp9RvuR95kVjir0e6/BvEmGbc=
-golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f h1:W3F4c+6OLc6H2lb//N1q4WpJkhzJCK5J6kUi1NTVXfM=
-golang.org/x/exp v0.0.0-20260410095643-746e56fc9e2f/go.mod h1:J1xhfL/vlindoeF/aINzNzt2Bket5bjo9sdOYzOsU80=
+golang.org/x/crypto v0.53.0 h1:QZ4Muo8THX6CizN2vPPd5fBGHyogrdK9fG4wLPFUsto=
+golang.org/x/crypto v0.53.0/go.mod h1:DNLU434OwVakk9PzuwV8w62mAJpRJL3vsgcfp4Qnsio=
+golang.org/x/exp v0.0.0-20260603202125-055de637280b h1:v1uXiEBHo8QA0LiGCo7UgHMzHT4Kdfpl2zmtH5vaP1Q=
+golang.org/x/exp v0.0.0-20260603202125-055de637280b/go.mod h1:d2fgXJLVs4dYDHUk5lwMIfzRzSrWCfGZb0ZqeLa/Vcw=
 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.38.0 h1:MECBjubtXD7yj4HrhIUcywNaGeNVUdfVnxmPajOk4yk=
@@ -196,16 +198,16 @@ golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.45.0 h1:dO4czNzziLiiXplLQgBCEpCvXQ3dnkn0SdaZSYdQ+FY=
-golang.org/x/sys v0.45.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/sys v0.46.0 h1:noSf2Fq6F8DBgS+LysIkx7rIExoNHJsxOAtPp4rthXw=
+golang.org/x/sys v0.46.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
-golang.org/x/term v0.43.0 h1:S4RLU2sB31O/NCl+zFN9Aru9A/Cq2aqKpTZJ6B+DwT4=
-golang.org/x/term v0.43.0/go.mod h1:lrhlHNdQJHO+1qVYiHfFKVuVioJIheAc3fBSMFYEIsk=
+golang.org/x/term v0.44.0 h1:0rLvDRCtNj0gZkyIXhCyOb2OAzEhLVqc4B+hrsBhrmc=
+golang.org/x/term v0.44.0/go.mod h1:7ze4MdzUzLXpSAoFP1H0bOI9aXDqveSvatT5vKcFh2Y=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
-golang.org/x/text v0.37.0 h1:Cqjiwd9eSg8e0QAkyCaQTNHFIIzWtidPahFWR83rTrc=
-golang.org/x/text v0.37.0/go.mod h1:a5sjxXGs9hsn/AJVwuElvCAo9v8QYLzvavO5z2PiM38=
+golang.org/x/text v0.38.0 h1:sXmwo9DwP3OK9EZ7PqAdaooSGozfl/3a6/xJcbzPRhE=
+golang.org/x/text v0.38.0/go.mod h1:YXZt3QhHUKYT53r2lLKFIVi6Ao1jdzrTR/KQ09qyxF4=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20200619180055-7c47624df98f/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
@@ -230,5 +232,3 @@ gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 k8s.io/klog/v2 v2.140.0 h1:Tf+J3AH7xnUzZyVVXhTgGhEKnFqye14aadWv7bzXdzc=
 k8s.io/klog/v2 v2.140.0/go.mod h1:o+/RWfJ6PwpnFn7OyAG3QnO47BFsymfEfrz6XyYSSp0=
-rsc.io/tmp/mpt v0.2.0 h1:EORjerXrh5u8VU0INROMFgclr2HVO2XzSx9j4wmsTak=
-rsc.io/tmp/mpt v0.2.0/go.mod h1:aP1ILCaUW9I5rFbt2z0/8KYz/0FDaYfPW2zEArs+OIQ=
diff --git a/vindex/client/client.go b/vindex/client/client.go
index 10cff6d..9201a7e 100644
--- a/vindex/client/client.go
+++ b/vindex/client/client.go
@@ -16,7 +16,6 @@
 package client
 
 import (
-	"bytes"
 	"context"
 	"crypto/sha256"
 	"encoding/binary"
@@ -37,7 +36,7 @@ import (
 	"github.com/transparency-dev/tessera/client"
 	"golang.org/x/mod/sumdb/note"
 	"k8s.io/klog/v2"
-	"rsc.io/tmp/mpt"
+	"filippo.io/torchwood/mpt"
 )
 
 func VerifyLookupResponse(keyHash [sha256.Size]byte, resp api.LookupResponse, inV, outV note.Verifier) ([]uint64, []byte, error) {
@@ -84,19 +83,20 @@ func VerifyLookupResponse(keyHash [sha256.Size]byte, resp api.LookupResponse, in
 		return nil, nil, fmt.Errorf("failed to parse input log checkpoint: %v", err)
 	}
 
+	expectFound := len(resp.IndexValue) > 0
+	var val []byte
+	if expectFound {
+		val = vindexLeafHash
+	}
+
 	snap := mpt.Snapshot{
 		Version: int64(ilcp.Size),
 		Hash:    mapRoot,
 	}
-	kvHash, ok, err := mpt.Verify(snap, keyHash, resp.IndexProof)
-	if err != nil {
+	if err := mpt.Verify(snap, keyHash[:], val, expectFound, resp.IndexProof); err != nil {
 		return nil, nil, fmt.Errorf("mpt.Verify(): %v", err)
 	}
 
-	if ok && !bytes.Equal(kvHash[:], vindexLeafHash) {
-		return nil, nil, fmt.Errorf("failed to verify membership: %x != %x", kvHash, vindexLeafHash)
-	}
-
 	return resp.IndexValue, inCp, nil
 }
 
diff --git a/vindex/map.go b/vindex/map.go
index 9361e48..00b9ace 100644
--- a/vindex/map.go
+++ b/vindex/map.go
@@ -44,7 +44,7 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/metric"
 	"k8s.io/klog/v2"
-	"rsc.io/tmp/mpt"
+	"filippo.io/torchwood/mpt"
 )
 
 const (
@@ -514,7 +514,7 @@ func (b *VerifiableIndex) Lookup(ctx context.Context, key [sha256.Size]byte) (ap
 	lookupLocked := func(key [sha256.Size]byte) (mpt.Proof, []uint64, error) {
 		b.indexMu.RLock()
 		defer b.indexMu.RUnlock()
-		proof, err := b.vindex.Prove(key)
+		_, _, proof, err := b.vindex.Prove(key)
 		return proof, b.data[key], err
 	}
 
@@ -570,17 +570,25 @@ func (b *VerifiableIndex) Lookup(ctx context.Context, key [sha256.Size]byte) (ap
 	if size > math.MaxInt64 {
 		return result, fmt.Errorf("size %d exceeds MaxInt64", size)
 	}
+	expectFound := len(result.IndexValue) > 0
+	var val []byte
+	if expectFound {
+		sum := sha256.New()
+		for _, idx := range result.IndexValue {
+			if err := binary.Write(sum, binary.BigEndian, idx); err != nil {
+				return result, fmt.Errorf("failed to calculate expected value hash: %v", err)
+			}
+		}
+		val = sum.Sum(nil)
+	}
+
 	snap := mpt.Snapshot{
 		Version: int64(size),
 		Hash:    mapRoot,
 	}
-	_, ok, err := mpt.Verify(snap, key, viProof)
-	if err != nil {
+	if err := mpt.Verify(snap, key[:], val, expectFound, viProof); err != nil {
 		return result, fmt.Errorf("failed to verify proof: %v", err)
 	}
-	if expectFound := len(result.IndexValue) > 0; expectFound != ok {
-		return result, fmt.Errorf("ok = %t, but expected %t (number of indices: %d)", ok, expectFound, len(result.IndexValue))
-	}
 	result.IndexProof = viProof
 
 	return result, nil