diff --git a/eth/downloader/beaconsync.go b/eth/downloader/beaconsync.go
index 33ad0f8971..12b74a1ba9 100644
--- a/eth/downloader/beaconsync.go
+++ b/eth/downloader/beaconsync.go
@@ -250,6 +250,9 @@ func (d *Downloader) findBeaconAncestor() (uint64, error) {
 		check := (start + end) / 2
 
 		h := d.skeleton.Header(check)
+		if h == nil {
+			return 0, fmt.Errorf("filled skeleton header is missing: %d", check)
+		}
 		n := h.Number.Uint64()
 
 		var known bool
diff --git a/eth/downloader/skeleton.go b/eth/downloader/skeleton.go
index 206d28414e..2cf9c4672b 100644
--- a/eth/downloader/skeleton.go
+++ b/eth/downloader/skeleton.go
@@ -1150,6 +1150,9 @@ func (s *skeleton) cleanStales(filled *types.Header) error {
 	if number < s.progress.Subchains[0].Head {
 		// The skeleton chain is partially consumed, set the new tail as filled+1.
 		tail := rawdb.ReadSkeletonHeader(s.db, number+1)
+		if tail == nil {
+			return fmt.Errorf("filled header is missing: %d", number+1)
+		}
 		if tail.ParentHash != filled.Hash() {
 			return fmt.Errorf("filled header is discontinuous with subchain: %d %s, please file an issue", number, filled.Hash())
 		}