diff --git a/types/polymer/index.d.ts b/types/polymer/index.d.ts
index 7b7d45d572..c6a0dab4ea 100644
--- a/types/polymer/index.d.ts
+++ b/types/polymer/index.d.ts
@@ -185,7 +185,7 @@ declare global {
 
       // XStyling
 
-      updateStyles?(): void;
+      updateStyles?(styles?: {[prop: string]: string;}): void;
 
       /* common api */