diff --git a/conf/config.ini b/conf/config.ini
index b47bd65..9b71fd5 100644
--- a/conf/config.ini
+++ b/conf/config.ini
@@ -6,5 +6,5 @@ PDF_STORAGE_PATH=__DATA_DIR__
 
 # Digital signature configuration
 NSS3_DIRECTORY=__DATA_DIR__/nss/
-NSS3_PASSWORD=
-NSS3_NICK=
+NSS3_PASSWORD=__NSS3__PASSWORD__
+NSS3_NICK=__NSS3_NICK__
diff --git a/scripts/upgrade b/scripts/upgrade
index 0213457..a057fcd 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -9,6 +9,21 @@
 source _common.sh
 source /usr/share/yunohost/helpers
 
+#=================================================
+# ENSURE DOWNWARD COMPATIBILITY
+#=================================================
+ynh_script_progression --message="Ensuring downward compatibility..."
+
+if [ -z ${nss3_nick:-} ]; then
+    nss3_nick=""
+    ynh_app_setting_set --app=$app --key=nss3_nick --value=""
+fi
+
+if [ -z ${nss3_password:-} ]; then
+    nss3_password=""
+    ynh_app_setting_set --app=$app --key=nss3_password --value=""
+fi
+
 #=================================================
 # DOWNLOAD, CHECK AND UNPACK SOURCE
 #=================================================