diff --git a/lib/types.d.ts b/lib/types.d.ts
index ef9fd665..d97c89af 100644
--- a/lib/types.d.ts
+++ b/lib/types.d.ts
@@ -177,9 +177,9 @@ export interface TransformOptions {
   ts?: boolean;
   retainLines?: boolean;
   interopDefault?: boolean;
-  async: boolean;
+  async?: boolean;
   jsx?: boolean | JSXOptions;
-  [key: string]: any;
+  babel?: Record<string, any>;
 }
 
 export interface TransformResult {