diff --git a/types/index.d.ts b/types/index.d.ts
index 8b8c6f70b..af7f204af 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -844,7 +844,8 @@ declare module "jspdf" {
       ry: number,
       style?: string | null
     ): jsPDF;
-    save(filename?: string, options?: { returnPromise?: boolean }): jsPDF;
+    save(filename: string, options: { returnPromise: true }): Promise<void>;
+    save(filename?: string): jsPDF;
     saveGraphicsState(): jsPDF;
     setCharSpace(charSpace: number): jsPDF;
     setCreationDate(date?: Date | string): jsPDF;