diff --git a/composer.json b/composer.json
index a8d06927a06..f982eb36dce 100644
--- a/composer.json
+++ b/composer.json
@@ -34,7 +34,7 @@
         "monolog/monolog": "^3.8",
         "nikic/php-parser": "^5.3",
         "psr/container": "^2.0",
-        "psr/http-message": "^1",
+        "psr/http-message": "^2.0",
         "sebastian/diff": "^6.0",
         "sensiolabs/ansi-to-html": "^1.2",
         "silverstripe/config": "^3",
diff --git a/tests/php/View/Embed/MockRequest.php b/tests/php/View/Embed/MockRequest.php
index c92af57733b..0e3d2cec741 100644
--- a/tests/php/View/Embed/MockRequest.php
+++ b/tests/php/View/Embed/MockRequest.php
@@ -5,6 +5,7 @@
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\UriInterface;
 use Psr\Http\Message\StreamInterface;
+use Psr\Http\Message\MessageInterface;
 
 class MockRequest implements RequestInterface
 {
@@ -17,80 +18,88 @@ public function __construct(EmbedUnitTest $unitTest, MockUri $mockUri)
         $this->mockUri = $mockUri;
     }
 
-    public function getRequestTarget()
+    public function getRequestTarget(): string
     {
+        return '';
     }
 
-    public function getMethod()
+    public function getMethod(): string
     {
+        return '';
     }
 
-    public function getUri()
+    public function getUri(): UriInterface
     {
         $this->unitTest->setFirstRequest(false);
         return $this->mockUri;
     }
 
-    public function getProtocolVersion()
+    public function getProtocolVersion(): string
     {
+        return '';
     }
 
-    public function getHeaders()
+    public function getHeaders(): array
     {
+        return [];
     }
 
-    public function getHeader($name)
+    public function getHeader($name): array
     {
+        return [];
     }
 
-    public function getHeaderLine($name)
+    public function getHeaderLine($name): string
     {
+        return '';
     }
 
-    public function getBody()
+    public function getBody(): StreamInterface
     {
+        return MockUtil::createStreamInterface('');
     }
 
-    public function hasHeader($name)
+    public function hasHeader($name): bool
     {
+        return false;
     }
 
-    public function withHeader($name, $value)
+    public function withHeader($name, $value): MessageInterface
     {
         return $this;
     }
 
-    public function withAddedHeader($name, $value)
+    public function withAddedHeader($name, $value): MessageInterface
     {
         return $this;
     }
 
-    public function withoutHeader($name)
+    public function withoutHeader($name): MessageInterface
     {
         return $this;
     }
 
-    public function withBody(StreamInterface $body)
+    public function withBody(StreamInterface $body): MessageInterface
     {
         return $this;
     }
 
-    public function withProtocolVersion($version)
+    public function withProtocolVersion($version): MessageInterface
     {
         return $this;
     }
 
-    public function withRequestTarget($requestTarget)
+    public function withRequestTarget($requestTarget): RequestInterface
     {
         return $this;
     }
 
-    public function withMethod($method)
+    public function withMethod($method): RequestInterface
     {
         return $this;
     }
 
-    public function withUri(UriInterface $uri, $preserveHost = false)
+    public function withUri(UriInterface $uri, $preserveHost = false): RequestInterface
     {
         return $this;
     }
diff --git a/tests/php/View/Embed/MockResponse.php b/tests/php/View/Embed/MockResponse.php
index 65785047afd..477ba360eeb 100644
--- a/tests/php/View/Embed/MockResponse.php
+++ b/tests/php/View/Embed/MockResponse.php
@@ -4,6 +4,7 @@
 
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\StreamInterface;
+use Psr\Http\Message\MessageInterface;
 
 class MockResponse implements ResponseInterface
 {
@@ -18,78 +19,78 @@ public function __construct(EmbedUnitTest $unitTest, string $firstResponse, stri
         $this->secondResponse = $secondResponse;
     }
 
-    public function getStatusCode()
+    public function getStatusCode(): int
     {
         return 200;
     }
 
-    public function getBody()
+    public function getBody(): StreamInterface
     {
         // first request is to the video HTML to get to find the oembed link
         // second request is to the oembed endpoint to fetch JSON
         if ($this->unitTest->getFirstRequest()) {
-            return $this->firstResponse;
+            return MockUtil::createStreamInterface($this->firstResponse);
         } else {
-            return $this->secondResponse;
+            return MockUtil::createStreamInterface($this->secondResponse);
         }
     }
 
-    public function getReasonPhrase()
+    public function getReasonPhrase(): string
     {
         return '';
     }
 
-    public function getProtocolVersion()
+    public function getProtocolVersion(): string
     {
         return '';
     }
 
-    public function getHeaders()
+    public function getHeaders(): array
     {
         return [];
     }
 
-    public function getHeader($name)
+    public function getHeader($name): array
     {
-        return '';
+        return [];
     }
 
-    public function getHeaderLine($name)
+    public function getHeaderLine($name): string
     {
         return '';
     }
 
-    public function hasHeader($name)
+    public function hasHeader($name): bool
     {
         return false;
     }
 
-    public function withHeader($name, $value)
+    public function withHeader($name, $value): MessageInterface
     {
         return $this;
     }
 
-    public function withAddedHeader($name, $value)
+    public function withAddedHeader($name, $value): MessageInterface
     {
         return $this;
     }
 
-    public function withBody(StreamInterface $body)
+    public function withBody(StreamInterface $body): MessageInterface
     {
         return $this;
     }
 
-    public function withoutHeader($name)
+    public function withoutHeader($name): MessageInterface
     {
         return $this;
     }
 
-    public function withProtocolVersion($version)
+    public function withProtocolVersion($version): MessageInterface
     {
         return $this;
     }
 
-    public function withStatus($code, $reasonPhrase = '')
+    public function withStatus($code, $reasonPhrase = ''): ResponseInterface
     {
         return $this;
     }
diff --git a/tests/php/View/Embed/MockUri.php b/tests/php/View/Embed/MockUri.php
index a374d1336d2..e7a692d72cf 100644
--- a/tests/php/View/Embed/MockUri.php
+++ b/tests/php/View/Embed/MockUri.php
@@ -7,10 +7,10 @@
 
 class MockUri implements UriInterface, Stringable
 {
-    private string $scheme;
-    private string $host;
-    private string $path;
-    private string $query;
+    private string $scheme = '';
+    private string $host = '';
+    private string $path = '';
+    private string $query = '';
 
     public function __construct(string $url)
     {
@@ -21,73 +21,77 @@ public function __construct(string $url)
         $this->query = $p['query'] ?? '';
     }
 
-    public function getScheme()
+    public function getScheme(): string
     {
         return $this->scheme;
     }
 
-    public function getHost()
+    public function getHost(): string
     {
         return $this->host;
     }
 
-    public function getPath()
+    public function getPath(): string
     {
         return $this->path;
     }
 
-    public function getQuery()
+    public function getQuery(): string
     {
         return $this->query;
     }
 
-    public function getPort()
+    public function getPort(): ?int
     {
+        return null;
     }
 
-    public function getAuthority()
+    public function getAuthority(): string
     {
+        return '';
     }
 
-    public function getUserInfo()
+    public function getUserInfo(): string
     {
+        return '';
     }
 
-    public function getFragment()
+    public function getFragment(): string
     {
+        return '';
     }
 
-    public function withPath($path)
+    public function withPath($path): UriInterface
     {
         return $this;
     }
 
-    public function withScheme($scheme)
+    public function withScheme($scheme): UriInterface
     {
         return $this;
     }
 
-    public function withUserInfo($user, $password = null)
+    public function withUserInfo($user, $password = null): UriInterface
     {
         return $this;
     }
 
-    public function withHost($host)
+    public function withHost($host): UriInterface
     {
         return $this;
     }
 
-    public function withPort($port)
+    public function withPort($port): UriInterface
     {
         return $this;
     }
 
-    public function withQuery($query)
+    public function withQuery($query): UriInterface
     {
         return $this;
     }
 
-    public function withFragment($fragment)
+    public function withFragment($fragment): UriInterface
     {
         return $this;
     }
diff --git a/tests/php/View/Embed/MockUtil.php b/tests/php/View/Embed/MockUtil.php
new file mode 100644
index 00000000000..82000a9f035
--- /dev/null
+++ b/tests/php/View/Embed/MockUtil.php
@@ -0,0 +1,79 @@
+<?php
+
+namespace SilverStripe\View\Tests\Embed;
+
+use Psr\Http\Message\StreamInterface;
+
+class MockUtil
+{
+    public static function createStreamInterface(string $body)
+    {
+        return new class($body) implements StreamInterface {
+            private string $body;
+            public function __construct(string $body)
+            {
+                $this->body = $body;
+            }
+            public function __toString(): string
+            {
+                return $this->body;
+            }
+            public function close(): void
+            {
+                return;
+            }
+            public function detach()
+            {
+                return;
+            }
+            public function getSize(): ?int
+            {
+                return null;
+            }
+            public function tell(): int
+            {
+                return 0;
+            }
+            public function eof(): bool
+            {
+                return false;
+            }
+            public function isSeekable(): bool
+            {
+                return false;
+            }
+            public function seek(int $offset, int $whence = SEEK_SET): void
+            {
+                return;
+            }
+            public function rewind(): void
+            {
+                return;
+            }
+            public function isWritable(): bool
+            {
+                return false;
+            }
+            public function write(string $string): int
+            {
+                return 0;
+            }
+            public function isReadable(): bool
+            {
+                return false;
+            }
+            public function read(int $length): string
+            {
+                return '';
+            }
+            public function getContents(): string
+            {
+                return '';
+            }
+            public function getMetadata(?string $key = null)
+            {
+                return;
+            }
+        };
+    }
+}