diff --git a/google.visualization/google.visualization.d.ts b/google.visualization/google.visualization.d.ts
index 222faec1d..f1ef8278c 100644
--- a/google.visualization/google.visualization.d.ts
+++ b/google.visualization/google.visualization.d.ts
@@ -365,6 +365,7 @@ declare module google {
         export interface TransitionAnimation {
             duration?: number;
             easing?: string; // linear, in, out, inAndOut
+            startup?: boolean;
         }
 
         export interface ChartAxis {