diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 7fa0ea1..420cb9b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -39,6 +39,8 @@ jobs:
           - "8.0"
           - "8.1"
           - "8.2"
+          - "8.3"
+          - "8.4"
 
     steps:
       - name: Checkout.
diff --git a/.github/workflows/static.yml b/.github/workflows/static.yml
index 3e79b31..0d90f64 100644
--- a/.github/workflows/static.yml
+++ b/.github/workflows/static.yml
@@ -35,6 +35,7 @@ jobs:
           - "8.0"
           - "8.1"
           - "8.2"
+          - "8.3"
 
     steps:
       - name: Checkout.
diff --git a/src/Application.php b/src/Application.php
index cb874f0..cd16517 100644
--- a/src/Application.php
+++ b/src/Application.php
@@ -69,7 +69,7 @@ public function __construct(
      * @param ServerRequestInterface $request
      * @param RequestHandlerInterface|null $defaultHandler
      */
-    public function run(ServerRequestInterface $request, RequestHandlerInterface $defaultHandler = null): void
+    public function run(ServerRequestInterface $request, ?RequestHandlerInterface $defaultHandler = null): void
     {
         (new ServerRequestRunner($this->pipeline, $this->emitter))->run($request, $defaultHandler ?? $this->default);
     }
@@ -82,7 +82,7 @@ public function run(ServerRequestInterface $request, RequestHandlerInterface $de
      * @param mixed $middleware any valid value for converting it to `Psr\Http\Server\MiddlewareInterface` instance.
      * @param string|null $path path prefix from the root to which the middleware is attached.
      */
-    public function pipe($middleware, string $path = null): void
+    public function pipe($middleware, ?string $path = null): void
     {
         $this->pipeline->pipe($this->resolver->resolve($middleware), $path);
     }
diff --git a/src/Middleware/BodyParamsMiddleware.php b/src/Middleware/BodyParamsMiddleware.php
index dc72edd..5ba4662 100644
--- a/src/Middleware/BodyParamsMiddleware.php
+++ b/src/Middleware/BodyParamsMiddleware.php
@@ -27,8 +27,7 @@ final class BodyParamsMiddleware implements MiddlewareInterface
      *
      * @throws BadRequestHttpException
      * @link https://tools.ietf.org/html/rfc7231
-     * @psalm-suppress MixedArgument
-     * @psalm-suppress MixedAssignment
+     * @psalm-suppress MixedArgument, MixedAssignment, RiskyTruthyFalsyComparison
      */
     public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
     {