diff --git a/index.d.ts b/index.d.ts
index 31868c1..8f8f550 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -30,7 +30,7 @@ declare module 'react-cloudimage-responsive' {
     ratio?: number;
     lazyLoading?: boolean;
     lazyLoadConfig?: Record<string, any>;
-    doNotReplaceURL: boolean;
+    doNotReplaceURL?: boolean;
   }
 
   class BackgroundImg extends React.Component<ImgProps & React.ComponentProps<'img'>> { }