diff --git a/admin_manual/installation/source_installation.rst b/admin_manual/installation/source_installation.rst
index 6ac7fe0d3..25c3117f9 100644
--- a/admin_manual/installation/source_installation.rst
+++ b/admin_manual/installation/source_installation.rst
@@ -72,6 +72,7 @@ Database connectors (pick the one for your database:)
 * PHP module bz2 (recommended, required for extraction of apps)
 * PHP module intl (increases language translation performance and fixes sorting
   of non-ASCII characters)
+* PHP module sodium (only on RHEL/CentOS to use Argon2 for password hashing. If the password was hashed with Argon2 and the module is missing, your users can't log in.)
 
 Required for specific apps: