diff --git a/.gitignore b/.gitignore
index 9aedff4..1054073 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 vendor/
 .idea/
 composer.lock
+.phpunit.cache
 .phpunit.result.cache
 .vscode
 .php-cs-fixer.cache
diff --git a/composer.json b/composer.json
index a0dee1f..745e3d5 100644
--- a/composer.json
+++ b/composer.json
@@ -28,7 +28,7 @@
 
   },
   "require": {
-    "php": ">=8.0"
+    "php": ">=8.0 <8.3"
   },
   "require-dev": {
     "phpunit/phpunit": ">=9.0",
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index f591521..56bd7e0 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,20 +1,14 @@
 <?xml version="1.0" encoding="UTF-8"?>
-
-<phpunit backupGlobals="false"
-         backupStaticAttributes="false"
-         colors="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         convertDeprecationsToExceptions="true"
-         processIsolation="false"
-         stopOnFailure="false"
-         bootstrap="./tests/bootstrap.php"
-        >
-
-    <testsuites>
-        <testsuite name="Math Executor tests">
-            <directory>./tests/</directory>
-        </testsuite>
-    </testsuites>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  backupGlobals="false"
+  colors="true"
+  processIsolation="false"
+  stopOnFailure="false"
+  bootstrap="./tests/bootstrap.php"
+  xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.0/phpunit.xsd">
+  <testsuites>
+    <testsuite name="Math Executor tests">
+      <directory>./tests/</directory>
+    </testsuite>
+  </testsuites>
 </phpunit>
diff --git a/tests/MathTest.php b/tests/MathTest.php
index f8573d3..573b634 100644
--- a/tests/MathTest.php
+++ b/tests/MathTest.php
@@ -51,7 +51,7 @@ class MathTest extends TestCase
      *
      * @return array<array<string>>
      */
-    public function providerExpressions()
+    public static function providerExpressions()
     {
         return [
           ['-5'],
@@ -295,7 +295,7 @@ class MathTest extends TestCase
      *
      * @return array<array<string>>
      */
-    public function bcMathExpressions()
+    public static function bcMathExpressions()
     {
         return [
           ['-5'],
@@ -518,7 +518,7 @@ class MathTest extends TestCase
      *
      * @return array<array<string>>
      */
-    public function incorrectExpressions()
+    public static function incorrectExpressions()
     {
         return [
           ['1 * + '],
@@ -1091,7 +1091,7 @@ class MathTest extends TestCase
      *
      * @return array<array<mixed>>
      */
-    public function providerExpressionValues()
+    public static function providerExpressionValues()
     {
         return [
           ['arccos(0.5)', \acos(0.5)],