diff --git a/EnvelopeGenerator.Web/Middleware/CultureMiddleware.cs b/EnvelopeGenerator.Web/Middleware/CultureMiddleware.cs
index ea3200e6..a11c9c9a 100644
--- a/EnvelopeGenerator.Web/Middleware/CultureMiddleware.cs
+++ b/EnvelopeGenerator.Web/Middleware/CultureMiddleware.cs
@@ -22,7 +22,7 @@ public class CultureMiddleware
         var cookieName = CookieRequestCultureProvider.DefaultCookieName;
         var cookieValue = context.Request.Cookies[cookieName];
 
-        if (string.IsNullOrEmpty(cookieValue))
+        if (!_cultures.Languages.Contains(cookieValue))
         {
             var requestCulture = context.GetCultureByAcceptLanguage()?.Name;
             var culture = _cultures.GetOrDefault(requestCulture);