diff --git a/flot/jquery.flot.d.ts b/flot/jquery.flot.d.ts
index 542810545..1f6cf71cb 100644
--- a/flot/jquery.flot.d.ts
+++ b/flot/jquery.flot.d.ts
@@ -46,7 +46,7 @@ declare module jquery.flot {
         labelMargin?: number;
         axisMargin?: number;
         markings?: any;             //array of markings or (fn: axes -> array of markings)
-        borderWidth: number;
+        borderWidth?: any;          // number or width object
         borderColor?: any;          // color or null
         minBorderMargin?: number;       // or null
         clickable?: boolean;