diff --git a/CHANGELOG.md b/CHANGELOG.md
index d46fdda..22a7e6b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,8 +15,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
-- Work with HTTPlug 2, drop HTTPlug 1 support
-- Move to `react/http` library instead of `react/http-client`
+- Add full PSR-18 support.
+- Work with HTTPlug 2, drop HTTPlug 1 support.
+- Move to `react/http` library instead of `react/http-client`.
 
 ## [2.3.0] - 2019-07-30
 
diff --git a/src/Exception/UnexpectedValueException.php b/src/Exception/UnexpectedValueException.php
new file mode 100644
index 0000000..db6d8f4
--- /dev/null
+++ b/src/Exception/UnexpectedValueException.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Http\Adapter\React\Exception;
+
+use Http\Client\Exception;
+
+final class UnexpectedValueException extends \UnexpectedValueException implements Exception
+{
+}
diff --git a/src/Promise.php b/src/Promise.php
index f4df4cc..f522d65 100644
--- a/src/Promise.php
+++ b/src/Promise.php
@@ -2,6 +2,7 @@
 
 namespace Http\Adapter\React;
 
+use Http\Adapter\React\Exception\UnexpectedValueException;
 use Http\Client\Exception as HttplugException;
 use Http\Promise\Promise as HttpPromise;
 use Psr\Http\Message\RequestInterface;
@@ -9,7 +10,6 @@
 use React\EventLoop\LoopInterface;
 use React\Promise\PromiseInterface;
 use RuntimeException;
-use UnexpectedValueException;
 
 /**
  * React promise adapter implementation.
diff --git a/tests/PromiseTest.php b/tests/PromiseTest.php
index 85b63a4..288630c 100644
--- a/tests/PromiseTest.php
+++ b/tests/PromiseTest.php
@@ -2,6 +2,7 @@
 
 namespace Http\Adapter\React\Tests;
 
+use Http\Adapter\React\Exception\UnexpectedValueException;
 use Http\Adapter\React\Promise;
 use Http\Adapter\React\ReactFactory;
 use Http\Client\Exception\HttpException;
@@ -14,7 +15,6 @@
 use Psr\Http\Message\ResponseInterface;
 use React\Promise\Promise as ReactPromise;
 use RuntimeException;
-use UnexpectedValueException;
 
 class PromiseTest extends TestCase
 {