diff --git a/src/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php b/src/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php
index 7eebeb7a7234e..bf850c46c4a0e 100644
--- a/src/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php
+++ b/src/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php
@@ -37,6 +37,7 @@ public function __construct(array $data = array()) {
 	 * @param string $key Item key
 	 * @return boolean Does the item exist?
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetExists($key) {
 		$key = strtolower($key);
 		return isset($this->data[$key]);
@@ -48,6 +49,7 @@ public function offsetExists($key) {
 	 * @param string $key Item key
 	 * @return string|null Item value (null if offsetExists is false)
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetGet($key) {
 		$key = strtolower($key);
 		if (!isset($this->data[$key])) {
@@ -65,6 +67,7 @@ public function offsetGet($key) {
 	 * @param string $key Item name
 	 * @param string $value Item value
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetSet($key, $value) {
 		if ($key === null) {
 			throw new Requests_Exception('Object is a dictionary, not a list', 'invalidset');
@@ -79,6 +82,7 @@ public function offsetSet($key, $value) {
 	 *
 	 * @param string $key
 	 */
+	#[ReturnTypeWillChange]
 	public function offsetUnset($key) {
 		unset($this->data[strtolower($key)]);
 	}
@@ -88,6 +92,7 @@ public function offsetUnset($key) {
 	 *
 	 * @return ArrayIterator
 	 */
+	#[ReturnTypeWillChange]
 	public function getIterator() {
 		return new ArrayIterator($this->data);
 	}