diff --git a/src/Http/Middleware/PhpExtensionsChecking.php b/src/Http/Middleware/PhpExtensionsChecking.php
index c9be1f0ff4..3735be8b44 100644
--- a/src/Http/Middleware/PhpExtensionsChecking.php
+++ b/src/Http/Middleware/PhpExtensionsChecking.php
@@ -15,6 +15,7 @@ use Psr\Http\Server\MiddlewareInterface;
 use Psr\Http\Server\RequestHandlerInterface;
 
 use function __;
+use function defined;
 use function function_exists;
 use function sprintf;
 
@@ -86,6 +87,10 @@ final class PhpExtensionsChecking implements MiddlewareInterface
             Core::warnMissingExtension('session', true);
         }
 
+        if (! defined('SODIUM_CRYPTO_SECRETBOX_KEYBYTES')) {
+            Core::warnMissingExtension('sodium', true);
+        }
+
         /**
          * hash is required for cookie authentication.
          */