diff --git a/src/Container/Container.php b/src/Container/Container.php
index c66fb47..9569710 100644
--- a/src/Container/Container.php
+++ b/src/Container/Container.php
@@ -108,8 +108,7 @@
     public function has(string $id): bool
     {
         //return $this->definition($this->resolve($id)) !== null;
-        $name = $this->resolve($id);
-        return array_key_exists($name, $this->definitions) || class_exists($name);
+        return isset($this->definitions[$name = $this->resolve($id)]) || class_exists($name);
     }
     /** @inheritdoc*/
     public function get(string $id): mixed
@@ -163,7 +162,7 @@
      */
     private function definition(string $name): ?array
     {
-        if (array_key_exists($name, $this->definitions)) {
+        if (isset($this->definitions[$name])) {
             return $this->definitions[$name];
         } elseif (class_exists($name)) {
             $this->definitions[$name] = [
@@ -182,8 +181,8 @@
      */
     private function resolve(string $id): string
     {
-        while (array_key_exists($id, $this->definitions)) {
-            if (array_key_exists('alias', $this->definitions[$id])) {
+        while (isset($this->definitions[$id])) {
+            if (isset($this->definitions[$id]['alias'])) {
                 $id = $this->definitions[$id]['alias'];
             } else {
                 return $id;