diff --git a/triedb/pathdb/disklayer.go b/triedb/pathdb/disklayer.go
index 964ad2ef77..8631ea756d 100644
--- a/triedb/pathdb/disklayer.go
+++ b/triedb/pathdb/disklayer.go
@@ -262,8 +262,8 @@ func (dl *diskLayer) revert(h *history, loader triestate.TrieLoader) (*diskLayer
 
 // setBufferSize sets the node buffer size to the provided value.
 func (dl *diskLayer) setBufferSize(size int) error {
-	dl.lock.RLock()
-	defer dl.lock.RUnlock()
+	dl.lock.Lock()
+	defer dl.lock.Unlock()
 
 	if dl.stale {
 		return errSnapshotStale