diff --git a/vendor/github.com/hashicorp/go-immutable-radix/node.go b/vendor/github.com/hashicorp/go-immutable-radix/node.go
index 7a065e7..3ab904e 100644
--- a/vendor/github.com/hashicorp/go-immutable-radix/node.go
+++ b/vendor/github.com/hashicorp/go-immutable-radix/node.go
@@ -79,6 +79,18 @@
 	return -1, nil
 }
 
+func (n *Node) getLowerBoundEdge(label byte) (int, *Node) {
+	num := len(n.edges)
+	idx := sort.Search(num, func(i int) bool {
+		return n.edges[i].label >= label
+	})
+	// we want lower bound behavior so return even if it's not an exact match
+	if idx < num {
+		return idx, n.edges[idx].node
+	}
+	return -1, nil
+}
+
 func (n *Node) delEdge(label byte) {
 	num := len(n.edges)
 	idx := sort.Search(num, func(i int) bool {