diff --git a/package.json b/package.json
index 0f7a54c7..8e991847 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "radash",
-  "version": "12.1.0",
+  "version": "12.1.1",
   "description": "Functional utility library - modern, simple, typed, powerful",
   "main": "dist/cjs/index.cjs",
   "module": "dist/esm/index.mjs",
diff --git a/src/string.ts b/src/string.ts
index 40de090d..5dfcc54c 100644
--- a/src/string.ts
+++ b/src/string.ts
@@ -4,10 +4,11 @@
  * capitalize('hello')   -> 'Hello'
  * capitalize('va va voom') -> 'Va va voom'
  */
-export const capitalize = (str: string): string => {
-  if (!str || str.length === 0) return ''
+export const capitalize = <Str extends string>(str: Str): Capitalize<Str> => {
+  if (!str || str.length === 0) return '' as Capitalize<Str>
   const lower = str.toLowerCase()
-  return lower.substring(0, 1).toUpperCase() + lower.substring(1, lower.length)
+  return (lower.substring(0, 1).toUpperCase() +
+    lower.substring(1, lower.length)) as Capitalize<Str>
 }
 
 /**