diff --git a/random.js b/random.js
index ed8e2c4..1df672f 100644
--- a/random.js
+++ b/random.js
@@ -29,6 +29,10 @@ export const oneOf = arr => arr[math.floor(rand() * arr.length)]
 
 // @ts-ignore
 const uuidv4Template = [1e7] + -1e3 + -4e3 + -8e3 + -1e11
+
+/**
+ * @return {string}
+ */
 export const uuidv4 = () => uuidv4Template.replace(/[018]/g, /** @param {number} c */ c =>
   (c ^ uint32() & 15 >> c / 4).toString(16)
 )