diff --git a/addon/decorators/core-validator.js b/addon/decorators/core-validator.js
index b0e947f5..194416d0 100644
--- a/addon/decorators/core-validator.js
+++ b/addon/decorators/core-validator.js
@@ -1,6 +1,5 @@
 import { get, set } from '@ember/object';
 import { getOwner } from '@ember/application';
-import { capitalize } from '@ember/string';
 import { isEmpty, isBlank, isPresent, typeOf, isEqual } from '@ember/utils';
 import { A, isArray } from '@ember/array';
 
@@ -28,6 +27,11 @@ const Messages = {
   'sr-cyrl': MessagesSrCyrl,
 };
 
+function capitalize(str) {
+  if (typeof str !== 'string' || !str.length) return '';
+  return str.charAt(0).toUpperCase() + str.slice(1);
+}
+
 function coreValidator(constructor) {
   return class CoreValidator extends constructor {
     validationErrors = {};
diff --git a/package.json b/package.json
index dc4722a2..77923922 100644
--- a/package.json
+++ b/package.json
@@ -40,7 +40,6 @@
   },
   "devDependencies": {
     "@ember/optional-features": "^2.0.0",
-    "@ember/string": "^3.1.1",
     "@ember/test-helpers": "^2.8.1",
     "@embroider/test-setup": "^3.0.1",
     "@glimmer/component": "^1.1.2",
diff --git a/yarn.lock b/yarn.lock
index bf9687e3..2d8f058f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2042,13 +2042,6 @@
     mkdirp "^1.0.4"
     silent-error "^1.1.1"
 
-"@ember/string@^3.1.1":
-  version "3.1.1"
-  resolved "https://registry.yarnpkg.com/@ember/string/-/string-3.1.1.tgz#0a5ac0d1e4925259e41d5c8d55ef616117d47ff0"
-  integrity sha512-UbXJ+k3QOrYN4SRPHgXCqYIJ+yWWUg1+vr0H4DhdQPTy8LJfyqwZ2tc5uqpSSnEXE+/1KopHBE5J8GDagAg5cg==
-  dependencies:
-    ember-cli-babel "^7.26.6"
-
 "@ember/test-helpers@*", "@ember/test-helpers@^2.8.1":
   version "2.9.3"
   resolved "https://registry.yarnpkg.com/@ember/test-helpers/-/test-helpers-2.9.3.tgz#c2a9d6ab1c367af92cf1a334f97eb19b8e06e6e1"