diff --git a/src/Monolog/Formatter/JsonFormatter.php b/src/Monolog/Formatter/JsonFormatter.php
index 7223d2823..48a7082fb 100644
--- a/src/Monolog/Formatter/JsonFormatter.php
+++ b/src/Monolog/Formatter/JsonFormatter.php
@@ -102,6 +102,9 @@ public function includeStacktraces(bool $include = true): self
         return $this;
     }
 
+    /**
+     * @return array<array|bool|float|int|stdClass|string|null>
+     */
     protected function normalizeRecord(LogRecord $record): array
     {
         $normalized = parent::normalizeRecord($record);