diff --git a/chain/actors/manifest.go b/chain/actors/manifest.go
index 4eecab352..23caa184b 100644
--- a/chain/actors/manifest.go
+++ b/chain/actors/manifest.go
@@ -13,7 +13,7 @@ import (
 	"github.com/filecoin-project/specs-actors/v8/actors/builtin/manifest"
 )
 
-var ManifestCids map[Version]cid.Cid = map[Version]cid.Cid{
+var manifestCids map[Version]cid.Cid = map[Version]cid.Cid{
 	// TODO fill in manifest CIDs for v8 and upwards once these are fixed
 }
 
@@ -30,6 +30,21 @@ type actorEntry struct {
 	version Version
 }
 
+func AddManifest(av Version, manifestCid cid.Cid) {
+	manifestMx.Lock()
+	defer manifestMx.Unlock()
+
+	manifestCids[av] = manifestCid
+}
+
+func GetManifest(av Version) (cid.Cid, bool) {
+	manifestMx.Lock()
+	defer manifestMx.Unlock()
+
+	c, ok := manifestCids[av]
+	return c, ok
+}
+
 func LoadManifests(ctx context.Context, store cbor.IpldStore) error {
 	// tests may invoke this concurrently, so we wrap it in a sync.Once
 	loadOnce.Do(func() { loadError = loadManifests(ctx, store) })
@@ -42,7 +57,7 @@ func loadManifests(ctx context.Context, store cbor.IpldStore) error {
 	manifests = make(map[Version]*manifest.Manifest)
 	actorMeta = make(map[cid.Cid]actorEntry)
 
-	for av, mfCid := range ManifestCids {
+	for av, mfCid := range manifestCids {
 		mf := &manifest.Manifest{}
 		if err := adtStore.Get(ctx, mfCid, mf); err != nil {
 			return xerrors.Errorf("error reading manifest for network version %d (cid: %s): %w", av, mfCid, err)
diff --git a/chain/consensus/filcns/upgrades.go b/chain/consensus/filcns/upgrades.go
index cced0c0f9..f580c0aeb 100644
--- a/chain/consensus/filcns/upgrades.go
+++ b/chain/consensus/filcns/upgrades.go
@@ -89,7 +89,7 @@ func legacyPreMigration(f LegacyPreMigrationFunc) stmgr.PreMigrationFunc {
 func DefaultUpgradeSchedule() stmgr.UpgradeSchedule {
 	var us stmgr.UpgradeSchedule
 
-	v8ManifestCid, ok := actors.ManifestCids[actors.Version8]
+	v8ManifestCid, ok := actors.GetManifest(actors.Version8)
 	if !ok {
 		v8ManifestCid = cid.Undef
 	}
diff --git a/chain/vm/fvm.go b/chain/vm/fvm.go
index 02f5e157e..5b52dd24e 100644
--- a/chain/vm/fvm.go
+++ b/chain/vm/fvm.go
@@ -265,7 +265,7 @@ func NewFVM(ctx context.Context, opts *VMOpts) (*FVM, error) {
 			return nil, xerrors.Errorf("mapping network version to actors version: %w", err)
 		}
 
-		c, ok := actors.ManifestCids[av]
+		c, ok := actors.GetManifest(av)
 		if !ok {
 			return nil, xerrors.Errorf("no manifest for custom bundle (actors version %d)", av)
 		}