diff --git a/ffiwrapper/types.go b/ffiwrapper/types.go
index 876226429..98612175d 100644
--- a/ffiwrapper/types.go
+++ b/ffiwrapper/types.go
@@ -37,6 +37,8 @@ type Verifier interface {
 	VerifySeal(abi.SealVerifyInfo) (bool, error)
 	VerifyWinningPoSt(ctx context.Context, info abi.WinningPoStVerifyInfo) (bool, error)
 	VerifyWindowPoSt(ctx context.Context, info abi.WindowPoStVerifyInfo) (bool, error)
+
+	GenerateWinningPoStSectorChallenge(context.Context, abi.RegisteredProof, abi.ActorID, abi.PoStRandomness, uint64) ([]uint64, error)
 }
 
 var ErrSectorNotFound = errors.New("sector not found")
diff --git a/ffiwrapper/verifier_cgo.go b/ffiwrapper/verifier_cgo.go
index 662ff8d67..bf9a60c50 100644
--- a/ffiwrapper/verifier_cgo.go
+++ b/ffiwrapper/verifier_cgo.go
@@ -14,11 +14,6 @@ import (
 	"github.com/filecoin-project/sector-storage/stores"
 )
 
-func (sb *Sealer) GenerateWinningPoStSectorChallenge(ctx context.Context, proofType abi.RegisteredProof, minerID abi.ActorID, randomness abi.PoStRandomness, eligibleSectorCount uint64) ([]uint64, error) {
-	randomness[31] = 0 // TODO: Not correct, fixme
-	return ffi.GenerateWinningPoStSectorChallenge(proofType, minerID, randomness, eligibleSectorCount)
-}
-
 func (sb *Sealer) GenerateWinningPoSt(ctx context.Context, minerID abi.ActorID, sectorInfo []abi.SectorInfo, randomness abi.PoStRandomness) ([]abi.PoStProof, error) {
 	randomness[31] = 0                                                                                                    // TODO: Not correct, fixme
 	privsectors, err := sb.pubSectorToPriv(ctx, minerID, sectorInfo, nil, abi.RegisteredProof.RegisteredWinningPoStProof) // TODO: FAULTS?
@@ -98,3 +93,8 @@ func (proofVerifier) VerifyWindowPoSt(ctx context.Context, info abi.WindowPoStVe
 
 	return ffi.VerifyWindowPoSt(info)
 }
+
+func (proofVerifier) GenerateWinningPoStSectorChallenge(ctx context.Context, proofType abi.RegisteredProof, minerID abi.ActorID, randomness abi.PoStRandomness, eligibleSectorCount uint64) ([]uint64, error) {
+	randomness[31] = 0 // TODO: Not correct, fixme
+	return ffi.GenerateWinningPoStSectorChallenge(proofType, minerID, randomness, eligibleSectorCount)
+}
diff --git a/go.mod b/go.mod
index fb39fc9ae..c18f6874f 100644
--- a/go.mod
+++ b/go.mod
@@ -9,7 +9,7 @@ require (
 	github.com/filecoin-project/go-paramfetch v0.0.1
 	github.com/filecoin-project/lotus v0.2.10
 	github.com/filecoin-project/specs-actors v0.0.0-20200409043918-e569f4a2f504
-	github.com/filecoin-project/specs-storage v0.0.0-20200410185809-9fbaaa08f275
+	github.com/filecoin-project/specs-storage v0.0.0-20200417134612-61b2d91a6102
 	github.com/gorilla/mux v1.7.4
 	github.com/hashicorp/go-multierror v1.0.0
 	github.com/ipfs/go-cid v0.0.5
diff --git a/go.sum b/go.sum
index 81e4bf5ee..41c719485 100644
--- a/go.sum
+++ b/go.sum
@@ -107,8 +107,8 @@ github.com/filecoin-project/lotus v0.2.10 h1:ijrj/nYdKu5GiMo9r1+Zcp2A4jKHSOMZ2WN
 github.com/filecoin-project/lotus v0.2.10/go.mod h1:om5PQA9ZT0lf16qI7Fz/ZGLn4LDCMqPC8ntZA9uncRE=
 github.com/filecoin-project/specs-actors v0.0.0-20200409043918-e569f4a2f504 h1:mwuAaqxKThl70+7FkGdFKVLdwaQZQ8XmscKdhSBBtnc=
 github.com/filecoin-project/specs-actors v0.0.0-20200409043918-e569f4a2f504/go.mod h1:mdJraXq5vMy0+/FqVQIrnNlpQ/Em6zeu06G/ltQ0/lA=
-github.com/filecoin-project/specs-storage v0.0.0-20200410185809-9fbaaa08f275 h1:6OTcpsTQBQM0f/A67oEi4E4YtYd6fzkMqbU8cPIWMMs=
-github.com/filecoin-project/specs-storage v0.0.0-20200410185809-9fbaaa08f275/go.mod h1:xJ1/xl9+8zZeSSSFmDC3Wr6uusCTxyYPI0VeNVSFmPE=
+github.com/filecoin-project/specs-storage v0.0.0-20200417134612-61b2d91a6102 h1:T3f/zkuvgtgqcXrb0NO3BicuveGOxxUAMPa/Yif2kuE=
+github.com/filecoin-project/specs-storage v0.0.0-20200417134612-61b2d91a6102/go.mod h1:xJ1/xl9+8zZeSSSFmDC3Wr6uusCTxyYPI0VeNVSFmPE=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/gbrlsnchs/jwt/v3 v3.0.0-beta.1/go.mod h1:0eHX/BVySxPc6SE2mZRoppGq7qcEagxdmQnA3dzork8=
 github.com/go-check/check v0.0.0-20180628173108-788fd7840127/go.mod h1:9ES+weclKsC9YodN5RgxqK/VD9HM9JsCSh7rNhMZE98=
diff --git a/mock/mock.go b/mock/mock.go
index d55b40f5a..5ed879ce0 100644
--- a/mock/mock.go
+++ b/mock/mock.go
@@ -258,10 +258,6 @@ func AddOpFinish(ctx context.Context) (context.Context, func()) {
 	}
 }
 
-func (mgr *SectorMgr) GenerateWinningPoStSectorChallenge(ctx context.Context, proofType abi.RegisteredProof, minerID abi.ActorID, randomness abi.PoStRandomness, eligibleSectorCount uint64) ([]uint64, error) {
-	panic("implement me")
-}
-
 func (mgr *SectorMgr) GenerateWinningPoSt(ctx context.Context, minerID abi.ActorID, sectorInfo []abi.SectorInfo, randomness abi.PoStRandomness) ([]abi.PoStProof, error) {
 	panic("implement me")
 }
@@ -330,6 +326,10 @@ func (m mockVerif) GenerateDataCommitment(pt abi.RegisteredProof, pieces []abi.P
 	return ffiwrapper.GenerateUnsealedCID(pt, pieces)
 }
 
+func (m mockVerif) GenerateWinningPoStSectorChallenge(ctx context.Context, proofType abi.RegisteredProof, minerID abi.ActorID, randomness abi.PoStRandomness, eligibleSectorCount uint64) ([]uint64, error) {
+	panic("implement me")
+}
+
 var MockVerifier = mockVerif{}
 
 var _ ffiwrapper.Verifier = MockVerifier