diff --git a/d3/d3.d.ts b/d3/d3.d.ts
index 2fe18dad8..6848ba4dd 100644
--- a/d3/d3.d.ts
+++ b/d3/d3.d.ts
@@ -1388,7 +1388,7 @@ declare module D3 {
             /**
             * convert the color to a string.
             */
-            toString(): Color;
+            toString(): string;
         }
 
         export interface RGBColor extends Color{