diff --git a/d3/d3.d.ts b/d3/d3.d.ts
index 880e379a92..6d4b43c0dc 100644
--- a/d3/d3.d.ts
+++ b/d3/d3.d.ts
@@ -3064,6 +3064,8 @@ declare namespace d3 {
         }
 
         export interface Partition<T extends partition.Node> {
+            (root: T): T[];
+
             nodes(root: T): T[];
 
             links(nodes: T[]): partition.Link<T>[];