diff --git a/src/MessageTrait.php b/src/MessageTrait.php
index e95d072a..2d842eb4 100644
--- a/src/MessageTrait.php
+++ b/src/MessageTrait.php
@@ -30,16 +30,14 @@ trait MessageTrait
     /**
      * List of all registered headers, as key => array of values.
      *
-     * @var array
-     * @psalm-var array<non-empty-string, list<string>>
+     * @var array<non-empty-string, list<string>>
      */
     protected $headers = [];
 
     /**
      * Map of normalized header name to original name used to register header.
      *
-     * @var array
-     * @psalm-var array<non-empty-string, non-empty-string>
+     * @var array<non-empty-string, non-empty-string>
      */
     protected $headerNames = [];
 
diff --git a/src/Request/ArraySerializer.php b/src/Request/ArraySerializer.php
index e3c10485..58fe17e4 100644
--- a/src/Request/ArraySerializer.php
+++ b/src/Request/ArraySerializer.php
@@ -70,10 +70,9 @@ public static function fromArray(array $serializedRequest): Request
     }
 
     /**
-     * @return mixed
      * @throws Exception\DeserializationException
      */
-    private static function getValueFromKey(array $data, string $key, ?string $message = null)
+    private static function getValueFromKey(array $data, string $key, ?string $message = null): mixed
     {
         if (isset($data[$key])) {
             return $data[$key];
diff --git a/src/Response/ArraySerializer.php b/src/Response/ArraySerializer.php
index 0828e798..ddbf17bc 100644
--- a/src/Response/ArraySerializer.php
+++ b/src/Response/ArraySerializer.php
@@ -68,10 +68,9 @@ public static function fromArray(array $serializedResponse): Response
     }
 
     /**
-     * @return mixed
      * @throws Exception\DeserializationException
      */
-    private static function getValueFromKey(array $data, string $key, ?string $message = null)
+    private static function getValueFromKey(array $data, string $key, ?string $message = null): mixed
     {
         if (isset($data[$key])) {
             return $data[$key];
diff --git a/src/Response/JsonResponse.php b/src/Response/JsonResponse.php
index f570a0a0..17928d38 100644
--- a/src/Response/JsonResponse.php
+++ b/src/Response/JsonResponse.php
@@ -43,8 +43,7 @@ class JsonResponse extends Response
         | JSON_HEX_QUOT
         | JSON_UNESCAPED_SLASHES;
 
-    /** @var mixed */
-    private $payload;
+    private mixed $payload;
 
     /**
      * Create a JSON response with the given data.
@@ -65,7 +64,7 @@ class JsonResponse extends Response
      * @throws Exception\InvalidArgumentException If unable to encode the $data to JSON.
      */
     public function __construct(
-        $data,
+        mixed $data,
         int $status = 200,
         array $headers = [],
         private int $encodingOptions = self::DEFAULT_JSON_FLAGS
diff --git a/src/Uri.php b/src/Uri.php
index 0c35fdc6..d6b1d498 100644
--- a/src/Uri.php
+++ b/src/Uri.php
@@ -52,7 +52,11 @@ class Uri implements UriInterface, Stringable
      */
     public const CHAR_UNRESERVED = 'a-zA-Z0-9_\-\.~\pL';
 
-    /** @var int[] Array indexed by valid scheme names to their corresponding ports. */
+    /**
+     * Array indexed by valid scheme names to their corresponding ports.
+     *
+     * @var array<string, positive-int>
+     */
     protected $allowedSchemes = [
         'http'  => 80,
         'https' => 443,