diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index cb1b4d11d..f80fe1d1b 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -8,7 +8,7 @@ jobs:
         strategy:
             matrix:
                 os: [ubuntu-latest, windows-latest]
-                php: ['8.0', '8.1', '8.2']
+                php: ['8.0', '8.1', '8.2', '8.3']
 
             fail-fast: false
 
diff --git a/composer.json b/composer.json
index bead361a3..42f4ec451 100644
--- a/composer.json
+++ b/composer.json
@@ -15,7 +15,7 @@
 		}
 	],
 	"require": {
-		"php": ">=8.0 <8.3"
+		"php": ">=8.0 <8.4"
 	},
 	"require-dev": {
 		"nette/tester": "^2.5",
diff --git a/readme.md b/readme.md
index ff2ab46c3..d63550c02 100644
--- a/readme.md
+++ b/readme.md
@@ -40,7 +40,7 @@ The recommended way to install is via Composer:
 composer require nette/utils
 ```
 
-- Nette Utils 4.0 is compatible with PHP 8.0 to 8.2
+- Nette Utils 4.0 is compatible with PHP 8.0 to 8.3
 - Nette Utils 3.2 is compatible with PHP 7.2 to 8.2
 - Nette Utils 3.1 is compatible with PHP 7.1 to 8.0
 - Nette Utils 3.0 is compatible with PHP 7.1 to 8.0
diff --git a/src/Utils/Reflection.php b/src/Utils/Reflection.php
index f5cf4d7c6..5a4f2ab75 100644
--- a/src/Utils/Reflection.php
+++ b/src/Utils/Reflection.php
@@ -221,7 +221,8 @@ private static function parseUseStatements(string $code, ?string $forClass = nul
 			$tokens = [];
 		}
 
-		$namespace = $class = $classLevel = $level = null;
+		$namespace = $class = null;
+		$classLevel = $level = 0;
 		$res = $uses = [];
 
 		$nameTokens = [T_STRING, T_NS_SEPARATOR, T_NAME_QUALIFIED, T_NAME_FULLY_QUALIFIED];
@@ -290,7 +291,7 @@ private static function parseUseStatements(string $code, ?string $forClass = nul
 
 				case ord('}'):
 					if ($level === $classLevel) {
-						$class = $classLevel = null;
+						$class = $classLevel = 0;
 					}
 
 					$level--;
diff --git a/tests/Utils/DateTime.modifyClone.phpt b/tests/Utils/DateTime.modifyClone.phpt
index 2560b3624..4003e77f0 100644
--- a/tests/Utils/DateTime.modifyClone.phpt
+++ b/tests/Utils/DateTime.modifyClone.phpt
@@ -28,6 +28,6 @@ Assert::notSame((string) $date, (string) $dolly2);
 
 Assert::exception(
 	fn() => $date->modifyClone('xx'),
-	Nette\InvalidArgumentException::class,
+	PHP_VERSION_ID >= 80300 ? DateMalformedStringException::class : Nette\InvalidArgumentException::class,
 	'DateTime::modify(): Failed to parse %a%',
 );