diff --git a/chain/sync.go b/chain/sync.go
index ccc52cf57..66bb8318c 100644
--- a/chain/sync.go
+++ b/chain/sync.go
@@ -349,6 +349,10 @@ func zipTipSetAndMessages(bs cbor.IpldStore, ts *types.TipSet, allbmsgs []*types
 
 	fts := &store.FullTipSet{}
 	for bi, b := range ts.Blocks() {
+		if msgc := len(bmi[bi]) + len(smi[bi]); msgc > build.BlockMessageLimit {
+			return nil, fmt.Errorf("block %q has too many messages (%d)", b.Cid(), msgc)
+		}
+
 		var smsgs []*types.SignedMessage
 		var smsgCids []cbg.CBORMarshaler
 		for _, m := range smi[bi] {
@@ -365,10 +369,6 @@ func zipTipSetAndMessages(bs cbor.IpldStore, ts *types.TipSet, allbmsgs []*types
 			bmsgCids = append(bmsgCids, &c)
 		}
 
-		if msgc := len(bmsgCids) + len(smsgCids); msgc > build.BlockMessageLimit {
-			return nil, fmt.Errorf("block %q has too many messages (%d)", b.Cid(), msgc)
-		}
-
 		mrcid, err := computeMsgMeta(bs, bmsgCids, smsgCids)
 		if err != nil {
 			return nil, err