diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cf214c8..c64ef6a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,6 +11,7 @@ jobs:
     strategy:
       matrix:
         php:
+          - 8.1
           - 8.0
           - 7.4
           - 7.3
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index b9f98b3..e259890 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -5,7 +5,8 @@
          xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
          bootstrap="vendor/autoload.php"
          colors="true"
-         cacheResult="false">
+         cacheResult="false"
+         convertDeprecationsToExceptions="true">
     <testsuites>
         <testsuite name="Stdio React Test Suite">
             <directory>./tests/</directory>
diff --git a/src/Readline.php b/src/Readline.php
index 1a82cae..b75650e 100644
--- a/src/Readline.php
+++ b/src/Readline.php
@@ -938,7 +938,7 @@ public function strwidth($str)
      */
     private function strsplit($str)
     {
-        return preg_split('//u', $str, null, PREG_SPLIT_NO_EMPTY);
+        return preg_split('//u', $str, -1, PREG_SPLIT_NO_EMPTY);
     }
 
     /**