diff --git a/trie/bintrie/store_ops.go b/trie/bintrie/store_ops.go
index 9a73c8bd64..1924978ad2 100644
--- a/trie/bintrie/store_ops.go
+++ b/trie/bintrie/store_ops.go
@@ -263,6 +263,12 @@ func (s *nodeStore) splitStemValuesInsert(existingRef nodeRef, newStem []byte, v
 	nRef := s.newInternalRef(int(existing.depth))
 	nNode := s.getInternal(nRef.Index())
 	existing.depth++
+	// The existing stem's on-disk path is derived from its depth via
+	// extendPathToGroupLeaf. Promoting its depth changes that path, so the
+	// stem must be re-flushed at the new path; otherwise the old blob (at
+	// the prior path) gets overwritten by the new ancestor internal blob
+	// and the stem's data has no on-disk home.
+	existing.dirty = true
 
 	bitKey := newStem[nNode.depth/8] >> (7 - (nNode.depth % 8)) & 1
 	if bitKey == bitStem {