diff --git a/pkg/services/tree/heap/ordered_slice.go b/pkg/services/tree/heap/ordered_slice.go
index 6752bb685..23efe216d 100644
--- a/pkg/services/tree/heap/ordered_slice.go
+++ b/pkg/services/tree/heap/ordered_slice.go
@@ -8,9 +8,13 @@ import (
 )
 
 type OrderedSlice struct {
-	nodes  []pilorama.NodeInfo
+	nodes  []node
 	sorted bool
 }
+type node struct {
+	filename []byte
+	info     *pilorama.NodeInfo
+}
 
 func NewOrderedSlice() *OrderedSlice {
 	return new(OrderedSlice)
@@ -18,7 +22,12 @@ func NewOrderedSlice() *OrderedSlice {
 
 func (s *OrderedSlice) Insert(infos ...pilorama.NodeInfo) {
 	s.sorted = false
-	s.nodes = append(s.nodes, infos...)
+	for i := range infos {
+		s.nodes = append(s.nodes, node{
+			filename: infos[i].Meta.GetAttr(pilorama.AttributeFilename),
+			info:     &infos[i],
+		})
+	}
 }
 
 func (s *OrderedSlice) IsEmpty() bool {
@@ -33,15 +42,15 @@ func (s *OrderedSlice) ExtractMin() pilorama.NodeInfo {
 
 	node := s.nodes[0]
 	s.nodes = s.nodes[1:]
-	return node
+	return *node.info
 }
 
-func sortByFilename(nodes []pilorama.NodeInfo) {
+func sortByFilename(nodes []node) {
 	if len(nodes) == 0 {
 		return
 	}
 	less := func(i, j int) bool {
-		return bytes.Compare(nodes[i].Meta.GetAttr(pilorama.AttributeFilename), nodes[j].Meta.GetAttr(pilorama.AttributeFilename)) < 0
+		return bytes.Compare(nodes[i].filename, nodes[j].filename) < 0
 	}
 	sort.Slice(nodes, less)
 }