diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 0355c33..fbb7289 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -8,7 +8,7 @@ jobs:
       fail-fast: false
       matrix:
         operating-system: [ubuntu-latest]
-        php-versions: ['7.4', '8.0', '8.1', '8.2', '8.3']
+        php-versions: ['7.4', '8.0', '8.1', '8.2', '8.3', '8.4', '8.5']
 
     steps:
     - name: Checkout
diff --git a/composer.json b/composer.json
index 5f1b5e7..c51d6c6 100644
--- a/composer.json
+++ b/composer.json
@@ -22,7 +22,7 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^9",
-        "vimeo/psalm": "^4.6",
+        "vimeo/psalm": "^4.6 || ^5.0 || ^6.0",
         "friendsofphp/php-cs-fixer": "^3.0"
     },
     "autoload": {
diff --git a/src/Connection/InetSocket.php b/src/Connection/InetSocket.php
index 93da2f7..0be021b 100644
--- a/src/Connection/InetSocket.php
+++ b/src/Connection/InetSocket.php
@@ -144,7 +144,7 @@ private function cutIntoMtuSizedPackets(array $messages): array
         if ($this->allowFragmentation()) {
             $message = join(self::LINE_DELIMITER, $messages) . self::LINE_DELIMITER;
 
-            $result = str_split($message, $this->maxPayloadSize);
+            $result = str_split($message, max(1, $this->maxPayloadSize));
 
             return $result ?: [];
         }