diff --git a/CHANGELOG.md b/CHANGELOG.md
index 487c18a..1212abe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,10 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/) and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [3.2.1] - 2018-10-24
+### Summary
+- Widen range of supported Zend Diactoros version
+
 ## [3.2.0] - 2018-09-19
 ### Summary
 - Added support for `PATCH` HTTP method
diff --git a/composer.json b/composer.json
index 369b281..c268f48 100644
--- a/composer.json
+++ b/composer.json
@@ -9,7 +9,7 @@
         "psr/http-server-handler": "^1.0",
         "psr/http-server-middleware": "^1.0",
         "psr/log": "^1.0",
-        "zendframework/zend-diactoros": "^1.3"
+        "zendframework/zend-diactoros": "^1.3 || ^2.0"
     },
     "suggest": {
         "firehed/inputobjects": "Pre-made Input components for validation"
diff --git a/src/Dispatcher.php b/src/Dispatcher.php
index 1ca3dee..365a60e 100644
--- a/src/Dispatcher.php
+++ b/src/Dispatcher.php
@@ -161,6 +161,8 @@ private function transformRequestToServerRequest(RequestInterface $request): Ser
         foreach ($request->getHeaders() as $name => $values) {
             $serverRequest = $serverRequest->withHeader($name, $values);
         }
+        // ZD2 hints the return type of withHeader to MessageInterface not SRI
+        assert($serverRequest instanceof ServerRequestInterface);
         return $serverRequest;
     }
 
diff --git a/tests/DispatcherTest.php b/tests/DispatcherTest.php
index a25507f..15014e7 100644
--- a/tests/DispatcherTest.php
+++ b/tests/DispatcherTest.php
@@ -92,6 +92,7 @@ public function testSetRequestReturnsSelf()
     {
         $d = new Dispatcher();
         $req = $this->createMock(RequestInterface::class);
+        $req->method('getMethod')->willReturn('GET');
         $req->method('getHeaders')->willReturn([]);
         $req->method('getBody')->willReturn($this->createMock(StreamInterface::class));
         $req->method('getUri')->willReturn($this->createMock(UriInterface::class));