diff --git a/Locale.php b/Locale.php
index 931400d4..fa2da7e5 100644
--- a/Locale.php
+++ b/Locale.php
@@ -85,7 +85,9 @@ public static function getFallback($locale): ?string
 
             array_pop($localeSubTags);
 
-            return locale_compose($localeSubTags);
+            $fallback = locale_compose($localeSubTags);
+
+            return false !== $fallback ? $fallback : null;
         }
 
         if (false !== $pos = strrpos($locale, '_')) {