diff --git a/src/Handler/LogLevelStrategy/FixedStrategy.php b/src/Handler/LogLevelStrategy/FixedStrategy.php
index 7a98fef..2cfbed1 100644
--- a/src/Handler/LogLevelStrategy/FixedStrategy.php
+++ b/src/Handler/LogLevelStrategy/FixedStrategy.php
@@ -45,8 +45,8 @@ final class FixedStrategy implements LogLevelStrategyInterface
      */
     public function __construct(
         string $defaultLevel = LogLevel::DEBUG,
-        string $exceptionLevel = null,
-        string $statsLevel = null
+        ?string $exceptionLevel = null,
+        ?string $statsLevel = null
     ) {
         $this->defaultLevel = $defaultLevel;
         $this->exceptionLevel = $exceptionLevel ?? $defaultLevel;
diff --git a/src/Handler/MultiRecordArrayHandler.php b/src/Handler/MultiRecordArrayHandler.php
index 0b804cf..b917965 100644
--- a/src/Handler/MultiRecordArrayHandler.php
+++ b/src/Handler/MultiRecordArrayHandler.php
@@ -33,7 +33,7 @@ final class MultiRecordArrayHandler extends AbstractHandler
      * @param int $summarySize The size to use for the summary of a truncated body
      */
     public function __construct(
-        LogLevelStrategyInterface $logLevelStrategy = null,
+        ?LogLevelStrategyInterface $logLevelStrategy = null,
         int $truncateSize = 3500,
         int $summarySize = 200
     ) {