diff --git a/Installation-instructions.md b/Installation-instructions.md
index c49b10a..87e8172 100644
--- a/Installation-instructions.md
+++ b/Installation-instructions.md
@@ -18,8 +18,8 @@ SnappyMail requires PHP 7.4 (or a newer version) with the following extensions:
 Optional extensions:
 * cURL
 * exif
-* gd
-* gmagick or imagemagick
+* gd, gmagick or imagemagick
+* gnupg
 * iconv
 * intl
 * ldap
@@ -27,6 +27,7 @@ Optional extensions:
 * PDO (MySQL/PostgreSQL/SQLite) (for contacts)
 * redis
 * Sodium
+* Tidy
 * uuid (PECL)
 * xxtea (PECL)
 * zip
@@ -57,6 +58,11 @@ chown -R www-data:www-data /var/www/webmail
 www.yourdomain.com/webmail?admin
 ```
 
+## Upgrade
+To upgrade the installation, you simply need to upload files from the new package overwriting existing files. Directory structure is organized to have each new version installed to a different directory. Only a few files will be actually overwritten (/index.php and /snappymail/v/VERSION).
+
+All the additional reconfiguration will be done by the product on next run.
+
 
 ## Webserver configuration
 ### Nginx