diff --git a/field.go b/field.go
index 69d08d504..02d7d9ce5 100644
--- a/field.go
+++ b/field.go
@@ -183,8 +183,8 @@ func (f *Field) Path() string { return f.path }
 // RowAttrStore returns the attribute storage.
 func (f *Field) RowAttrStore() AttrStore { return f.rowAttrStore }
 
-// MaxShard returns the max shard in the field.
-func (f *Field) MaxShard() uint64 {
+// maxShard returns the max shard in the field.
+func (f *Field) maxShard() uint64 {
 	f.mu.RLock()
 	defer f.mu.RUnlock()
 
diff --git a/index.go b/index.go
index 7217bb659..4b8b84ca8 100644
--- a/index.go
+++ b/index.go
@@ -220,7 +220,7 @@ func (i *Index) maxShard() uint64 {
 
 	max := i.remoteMaxShard
 	for _, f := range i.fields {
-		if shard := f.MaxShard(); shard > max {
+		if shard := f.maxShard(); shard > max {
 			max = shard
 		}
 	}