diff --git a/src/ControllerValueResolver.php b/src/ControllerValueResolver.php
index 7868e90..0f10b9c 100644
--- a/src/ControllerValueResolver.php
+++ b/src/ControllerValueResolver.php
@@ -7,6 +7,7 @@
 use Brick\Http\Request;
 use Brick\Di\ValueResolver;
 use Brick\Reflection\ReflectionTools;
+use ReflectionNamedType;
 
 /**
  * Resolves controller values in the application.
@@ -54,8 +55,9 @@ public function setRequest(Request $request) : void
      */
     public function getParameterValue(\ReflectionParameter $parameter)
     {
-        $class = $parameter->getClass();
-        if ($class && $class->getName() === Request::class) {
+        $type = $parameter->getType();
+
+        if ($type instanceof ReflectionNamedType && ! $type->allowsNull() && $type->getName() === Request::class) {
             return $this->request;
         }
 
diff --git a/src/Plugin/ObjectUnpackPlugin.php b/src/Plugin/ObjectUnpackPlugin.php
index 285dde3..b874615 100644
--- a/src/Plugin/ObjectUnpackPlugin.php
+++ b/src/Plugin/ObjectUnpackPlugin.php
@@ -15,6 +15,7 @@
 use Brick\Http\Exception\HttpNotFoundException;
 use Brick\Http\Exception\HttpBadRequestException;
 use Brick\Http\Exception\HttpInternalServerErrorException;
+use ReflectionNamedType;
 
 /**
  * Automatically converts type-hinted objects in controller parameters, from their string or array representation.
@@ -82,10 +83,10 @@ private function getParameters(ControllerReadyEvent $event) : array
      */
     private function getParameterValue(\ReflectionParameter $parameter, $value)
     {
-        $class = $parameter->getClass();
+        $type = $parameter->getType();
 
-        if ($class) {
-            $className = $class->getName();
+        if ($type instanceof ReflectionNamedType && ! $type->isBuiltin()) {
+            $className = $type->getName();
 
             if ($parameter->isVariadic()) {
                 $result = [];
diff --git a/src/Plugin/OnBeforeAfterPlugin.php b/src/Plugin/OnBeforeAfterPlugin.php
index 4f229e5..560358a 100644
--- a/src/Plugin/OnBeforeAfterPlugin.php
+++ b/src/Plugin/OnBeforeAfterPlugin.php
@@ -12,6 +12,7 @@
 use Brick\Http\Request;
 use Brick\Http\Response;
 use Brick\Reflection\ReflectionTools;
+use ReflectionNamedType;
 
 /**
  * Registers functions to be called before and after controller method invocation.
@@ -134,10 +135,10 @@ private function getFunctionParameters(string $onEvent, callable $function, arra
         $reflectionFunction = $this->reflectionTools->getReflectionFunction($function);
 
         foreach ($reflectionFunction->getParameters() as $reflectionParameter) {
-            $parameterClass = $reflectionParameter->getClass();
+            $parameterType = $reflectionParameter->getType();
 
-            if ($parameterClass !== null) {
-                $parameterClassName = $parameterClass->getName();
+            if ($parameterType instanceof ReflectionNamedType && ! $parameterType->isBuiltin()) {
+                $parameterClassName = $parameterType->getName();
 
                 if (isset($objects[$parameterClassName])) {
                     $parameters[] = $objects[$parameterClassName];
@@ -163,12 +164,12 @@ private function cannotResolveParameter(string $onEvent, array $types, \Reflecti
     {
         $message = 'Cannot resolve ' . $onEvent . ' function parameter $' . $parameter->getName() . ': ';
 
-        $parameterClass = $parameter->getClass();
+        $parameterType = $parameter->getType();
 
-        if ($parameterClass === null) {
+        if ($parameterType === null) {
             $message .= 'parameter is not typed.';
-        } else {
-            $message .= 'type ' . $parameterClass->getName() . ' is not in available types (' . implode(', ', $types) . ').';
+        } elseif ($parameterType instanceof ReflectionNamedType) {
+            $message .= 'type ' . $parameterType->getName() . ' is not in available types (' . implode(', ', $types) . ').';
         }
 
         return new HttpInternalServerErrorException($message);
diff --git a/src/Plugin/RequestParamPlugin.php b/src/Plugin/RequestParamPlugin.php
index 6f3d131..bf1473b 100644
--- a/src/Plugin/RequestParamPlugin.php
+++ b/src/Plugin/RequestParamPlugin.php
@@ -11,6 +11,7 @@
 use Brick\Http\Request;
 use Brick\Http\Exception\HttpBadRequestException;
 use Brick\Http\Exception\HttpInternalServerErrorException;
+use ReflectionNamedType;
 
 /**
  * Injects request parameters into controllers with the QueryParam and PostParam annotations.
@@ -108,15 +109,21 @@ private function getParameter(RequestParam $annotation, \ReflectionFunctionAbstr
 
         $value = $requestParameters[$parameterName];
 
-        if ($value === '' && $parameter->getClass() && $parameter->allowsNull()) {
+        $parameterType = $parameter->getType();
+
+        if ($value === '' && $parameterType instanceof ReflectionNamedType && ! $parameterType->isBuiltin() && $parameter->allowsNull()) {
             return null;
         }
 
-        if ($parameter->isArray() && ! is_array($value)) {
+        $isArray = $parameterType instanceof ReflectionNamedType && $parameterType->getName() === 'array';
+
+        if ($isArray && ! is_array($value)) {
             throw $this->invalidArrayParameterException($controller, $annotation);
         }
 
-        if ($parameter->isArray() || $parameter->getClass()) {
+        $hasClass = $parameterType instanceof ReflectionNamedType && ! $parameterType->isBuiltin();
+
+        if ($isArray || $hasClass) {
             return $value;
         }
 
@@ -126,6 +133,11 @@ private function getParameter(RequestParam $annotation, \ReflectionFunctionAbstr
             return $value;
         }
 
+        if (! $type instanceof ReflectionNamedType) {
+            // @todo handle union types
+            return $value;
+        }
+
         $type = $type->getName();
 
         if ($value === '') {