diff --git a/sharepoint/SharePoint.d.ts b/sharepoint/SharePoint.d.ts
index 0be396fe6..417ea1e2f 100644
--- a/sharepoint/SharePoint.d.ts
+++ b/sharepoint/SharePoint.d.ts
@@ -861,9 +861,9 @@ declare class Callout {
     /** Re-renders the actions menu. Call after the actions menu is changed. */
     refreshActions(): void;
     /** Display the callout. Animation can be used only for IE9+ */
-    open(useAnimation: boolean);
+    open(useAnimation?: boolean);
     /** Hide the callout. Animation can be used only for IE9+ */
-    close(useAnimation: boolean);
+    close(useAnimation?: boolean);
     /** Display if hidden, hide if shown. */
     toggle(): void;
     /** Do not call this directly. Instead, use CalloutManager.remove */