diff --git a/search/internals.go b/search/internals.go
index 9fd80126..a775e6cd 100644
--- a/search/internals.go
+++ b/search/internals.go
@@ -142,6 +142,20 @@ func (pq *aStarPriorityQueue) Exists(id int) bool {
 	return ok
 }
 
+type denseNodeSorter []gr.Node
+
+func (dns denseNodeSorter) Less(i, j int) bool {
+	return dns[i].ID() < dns[j].ID()
+}
+
+func (dns denseNodeSorter) Swap(i, j int) {
+	dns[i], dns[j] = dns[j], dns[i]
+}
+
+func (dns denseNodeSorter) Len() int {
+	return len(dns)
+}
+
 // General utility funcs
 
 // Rebuilds a path backwards from the goal.