diff -u -r src/Pimple/Container.php src/Pimple/Container.php
--- src/Pimple/Container.php	2020-11-24 12:35:42.000000000 -0800
+++ src/Pimple/Container.php	2022-10-17 17:46:39.676762448 -0700
@@ -76,6 +76,7 @@
      *
      * @throws FrozenServiceException Prevent override of a frozen service
      */
+    #[\ReturnTypeWillChange]
     public function offsetSet($id, $value)
     {
         if (isset($this->frozen[$id])) {
@@ -95,6 +96,7 @@
      *
      * @throws UnknownIdentifierException If the identifier is not defined
      */
+    #[\ReturnTypeWillChange]
     public function offsetGet($id)
     {
         if (!isset($this->keys[$id])) {
@@ -130,6 +132,7 @@
      *
      * @return bool
      */
+    #[\ReturnTypeWillChange]
     public function offsetExists($id)
     {
         return isset($this->keys[$id]);
@@ -140,6 +143,7 @@
      *
      * @param string $id The unique identifier for the parameter or object
      */
+    #[\ReturnTypeWillChange]
     public function offsetUnset($id)
     {
         if (isset($this->keys[$id])) {