diff --git a/geometry/Overview.bs b/geometry/Overview.bs
index 5aba6764..3afdc944 100644
--- a/geometry/Overview.bs
+++ b/geometry/Overview.bs
@@ -425,10 +425,10 @@ interface DOMQuad {
 };
 
 dictionary DOMQuadInit {
-  DOMPointInit p1;
-  DOMPointInit p2;
-  DOMPointInit p3;
-  DOMPointInit p4;
+  DOMPointInit p1 = null;
+  DOMPointInit p2 = null;
+  DOMPointInit p3 = null;
+  DOMPointInit p4 = null;
 };
 </pre>