diff --git a/d3/d3.d.ts b/d3/d3.d.ts
index f26538bd1..66a6e4d23 100644
--- a/d3/d3.d.ts
+++ b/d3/d3.d.ts
@@ -18,13 +18,13 @@ declare module D3 {
             *
             * @param selector Selection String to match
             */
-            (selector?: string): Selection;
+            (selector: string): Selection;
             /**
             * Selects the specified node
             *
             * @param element Node element to select
             */
-            (element?: EventTarget): Selection;
+            (element: EventTarget): Selection;
         };
 
         /**