diff --git a/phpunit.10.xml b/phpunit.10.xml
index 38fdee8..0820114 100644
--- a/phpunit.10.xml
+++ b/phpunit.10.xml
@@ -1,10 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/11.1/phpunit.xsd"
-         beStrictAboutOutputDuringTests="true"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd"
          bootstrap="vendor/autoload.php"
          cacheDirectory=".phpunit.cache"
          executionOrder="depends,defects"
+         beStrictAboutOutputDuringTests="true"
          failOnNotice="true"
          failOnRisky="true"
          failOnWarning="true">
@@ -14,10 +14,9 @@
         </testsuite>
     </testsuites>
 
-    <source restrictNotices="true" restrictWarnings="true">
+    <source restrictDeprecations="true" restrictNotices="true" restrictWarnings="true">
         <include>
             <directory>src</directory>
         </include>
     </source>
 </phpunit>
-
diff --git a/phpunit.9.xml b/phpunit.9.xml
new file mode 100644
index 0000000..023731a
--- /dev/null
+++ b/phpunit.9.xml
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.6/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
+         cacheResultFile=".phpunit.cache/test-results"
+         executionOrder="depends,defects"
+         beStrictAboutOutputDuringTests="true"
+         beStrictAboutTodoAnnotatedTests="true"
+         convertDeprecationsToExceptions="true"
+         failOnRisky="true"
+         failOnWarning="true"
+         verbose="true">
+    <testsuites>
+        <testsuite name="default">
+            <directory>tests</directory>
+        </testsuite>
+    </testsuites>
+
+    <coverage cacheDirectory=".phpunit.cache/code-coverage"
+              processUncoveredFiles="true">
+        <include>
+            <directory suffix=".php">src</directory>
+        </include>
+    </coverage>
+</phpunit>