diff --git a/composer.json b/composer.json
index 2e72316f21..d77e9341c3 100644
--- a/composer.json
+++ b/composer.json
@@ -33,7 +33,7 @@
     "require-dev" : {
         "ext-sqlite3": "*",
         "friendsofphp/php-cs-fixer": "^2.19",
-        "monolog/monolog": "^1.27",
+        "monolog/monolog": "^1.27 || ^2.0",
         "phpstan/phpstan": "^0.12 || ^1.0",
         "phpstan/phpstan-phpunit": "^1.0",
         "phpunit/phpunit": "^7.5 || ^8.5 || ^9.6"
diff --git a/tests/Sabre/DAV/MockLogger.php b/tests/Sabre/DAV/MockLogger.php
index 17e2f1dd9d..28e744f961 100644
--- a/tests/Sabre/DAV/MockLogger.php
+++ b/tests/Sabre/DAV/MockLogger.php
@@ -24,7 +24,7 @@ class MockLogger extends AbstractLogger
      * @param mixed  $level
      * @param string $message
      */
-    public function log($level, $message, array $context = [])
+    public function log($level, $message, array $context = []): void
     {
         $this->logs[] = [
             $level,