diff --git a/src/Monolog/Formatter/NormalizerFormatter.php b/src/Monolog/Formatter/NormalizerFormatter.php
index d4eb1afa..42786664 100644
--- a/src/Monolog/Formatter/NormalizerFormatter.php
+++ b/src/Monolog/Formatter/NormalizerFormatter.php
@@ -300,7 +300,9 @@ class NormalizerFormatter implements FormatterInterface
 
     protected function formatDate(\DateTimeInterface $date)
     {
-        if ($date instanceof DateTimeImmutable) {
+        // in case the date format isn't custom then we defer to the custom DateTimeImmutable
+        // formatting logic, which will pick the right format based on whether useMicroseconds is on
+        if ($this->dateFormat === self::SIMPLE_DATE && $date instanceof DateTimeImmutable) {
             return (string) $date;
         }