diff --git a/.npmignore b/.npmignore
index e764558..b28d752 100644
--- a/.npmignore
+++ b/.npmignore
@@ -2,6 +2,7 @@
 .github
 .nyc_output
 .travis.yml
+__pycache__/
 node_modules/
 coverage/
 rollup/
diff --git a/cjs/index.js b/cjs/index.js
index e519a19..7591f25 100644
--- a/cjs/index.js
+++ b/cjs/index.js
@@ -56,7 +56,7 @@ const set = (known, input, value) => {
 /**
  * Converts a specialized flatted string into a JS value.
  * @param {string} text
- * @param {((this: any, key: string, value: any) => any) | undefined): any} [reviver]
+ * @param {(this: any, key: string, value: any) => any} [reviver]
  * @returns {any}
  */
 const parse = (text, reviver) => {
diff --git a/index.js b/index.js
index 7575c95..faa281c 100644
--- a/index.js
+++ b/index.js
@@ -66,7 +66,7 @@ self.Flatted = (function (exports) {
   /**
    * Converts a specialized flatted string into a JS value.
    * @param {string} text
-   * @param {((this: any, key: string, value: any) => any) | undefined): any} [reviver]
+   * @param {(this: any, key: string, value: any) => any} [reviver]
    * @returns {any}
    */
   var parse = function parse(text, reviver) {