diff --git a/IntlExtension.php b/IntlExtension.php
index 0b33331..d932e7f 100644
--- a/IntlExtension.php
+++ b/IntlExtension.php
@@ -372,7 +372,7 @@ public function formatDateTime(Environment $env, $date, ?string $dateFormat = 'm
         $date = CoreExtension::dateConverter($env, $date, $timezone);
 
         $formatterTimezone = $timezone;
-        if (null === $formatterTimezone) {
+        if (null === $formatterTimezone || false === $formatterTimezone) {
             $formatterTimezone = $date->getTimezone();
         } elseif (\is_string($formatterTimezone)) {
             $formatterTimezone = new \DateTimeZone($timezone);