diff --git a/chain/sub/bcast/consistent.go b/chain/sub/bcast/consistent.go
index b69845476..cc600cb10 100644
--- a/chain/sub/bcast/consistent.go
+++ b/chain/sub/bcast/consistent.go
@@ -53,8 +53,16 @@ func (bd *bcastDict) store(key multihash.Multihash, d *blksInfo) {
 	bd.m.Store(key.String(), d)
 }
 
+func (bd *bcastDict) blkLen(key multihash.Multihash) int {
+	v, ok := bd.m.Load(key.String())
+	if !ok {
+		return 0
+	}
+	return len(v.(*blksInfo).blks)
+}
+
 type ConsistentBCast struct {
-	lk    sync.Mutex
+	lk    sync.RWMutex
 	delay time.Duration
 	// FIXME: Make this a slice??? Less storage but needs indexing logic.
 	m map[abi.ChainEpoch]*bcastDict
@@ -95,6 +103,8 @@ func (bInfo *blksInfo) eqErr() error {
 }
 
 func (cb *ConsistentBCast) Len() int {
+	cb.lk.RLock()
+	defer cb.lk.RUnlock()
 	return len(cb.m)
 }
 
@@ -121,7 +131,7 @@ func (cb *ConsistentBCast) RcvBlock(ctx context.Context, blk *types.BlockMsg) {
 		}
 
 		if !cidExists(bInfo.blks, blkCid) {
-			bInfo.blks = append(bInfo.blks, blkCid)
+			bcastDict.store(key, &blksInfo{bInfo.ctx, bInfo.cancel, append(bInfo.blks, blkCid)})
 			log.Errorf("equivocation detected for height %d: %s", blk.Header.Height, bInfo.eqErr())
 			return
 		}
@@ -133,7 +143,9 @@ func (cb *ConsistentBCast) RcvBlock(ctx context.Context, blk *types.BlockMsg) {
 }
 
 func (cb *ConsistentBCast) WaitForDelivery(bh *types.BlockHeader) error {
+	cb.lk.RLock()
 	bcastDict := cb.m[bh.Height]
+	cb.lk.RUnlock()
 	key, err := BCastKey(bh)
 	if err != nil {
 		return err
@@ -144,7 +156,7 @@ func (cb *ConsistentBCast) WaitForDelivery(bh *types.BlockHeader) error {
 	}
 	// Wait for the timeout
 	<-bInfo.ctx.Done()
-	if len(bInfo.blks) > 1 {
+	if bcastDict.blkLen(key) > 1 {
 		return fmt.Errorf("equivocation detected for epoch %d. Two blocks being broadcast with same VRFProof", bh.Height)
 	}
 	return nil