diff --git a/index.d.ts b/index.d.ts
index ebc9c1d..8d1a6ab 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -6,16 +6,18 @@ declare module "magic-string" {
 
   export interface SourceMapOptions {
     hires: boolean;
+    file: string;
+    source: string;
+    includeContent: boolean;
+  }
+
+  export interface SourceMap {
     file: string;
     sources: string[];
     sourcesContent: string;
-    includeContent: boolean;
     names: string[];
     mappings: string[];
-  }
 
-  class SourceMap {
-    constructor(properties: SourceMapOptions);
     toString(): string;
     toUrl(): string;
   }