diff --git a/index.d.ts b/index.d.ts
index 251701c..8404673 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -75,7 +75,7 @@ export interface OverwriteOptions {
 }
 
 export default class MagicString {
-  constructor(str: string, options?: MagicStringOptions);
+  constructor(str: string, options?: Partial<MagicStringOptions>);
   addSourcemapLocation(char: number): void;
   append(content: string): MagicString;
   appendLeft(index: number, content: string): MagicString;