diff --git a/src/Block/LocaleSwitcherBlockService.php b/src/Block/LocaleSwitcherBlockService.php
index <HASH>..<HASH> 100644
--- a/src/Block/LocaleSwitcherBlockService.php
+++ b/src/Block/LocaleSwitcherBlockService.php
@@ -71,7 +71,7 @@ class LocaleSwitcherBlockService extends AbstractBlockService
             ), E_USER_DEPRECATED);
 
             parent::__construct($templatingOrDeprecatedName, $showCountryFlagsOrTemplating);
-            $this->showCountryFlags = $showCountryFlags;
+            $this->showCountryFlags = $showCountryFlags ?? false;
         } else {
             throw new \TypeError(sprintf(
                 'Argument 2 passed to "%s()" must be either a "bool" value, "null" or an instance of "%s", %s given.',
Fix nullable value

$showCountryFlags could be nullable and the class property should
be boolean, there hasn't been a release yet, so there is no need
of changelog.