diff --git a/scripts/install b/scripts/install
index 73e565c..cf00df4 100755
--- a/scripts/install
+++ b/scripts/install
@@ -56,9 +56,9 @@ SETUP_SOURCE "dokuwiki-c5525093cf2c4f47e2e5d2439fe13964.tgz"
 sudo cp ../conf/dokuwiki.php $final_path/conf
 sudo cp ../conf/acl.auth.php $final_path/conf
 
-# Files owned by root, www-data can just read
-find $final_path -type f -print0 | sudo xargs -0 chmod 0644
-find $final_path -type d -print0 | sudo xargs -0 chmod 0755
+# Files owned by www-data can just read
+sudo find $final_path -type f -print0 | xargs -0 chmod 0644
+sudo find $final_path -type d -print0 | xargs -0 chmod 0755
 sudo chown -R www-data: $final_path
 
 # except for conf, data, some data subfolders, and lib/plugin, where www-data must have write permissions
diff --git a/scripts/upgrade b/scripts/upgrade
index f892aab..fea7a1a 100755
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -1,7 +1,7 @@
 #!/bin/bash
 
-# causes the shell to exit if any subcommand or pipeline returns a non-zero status
-set -e
+# Exit on command errors and treat unset variables as an error
+set -eu
 
 # Source app helpers
 source /usr/share/yunohost/helpers
@@ -59,10 +59,10 @@ sudo touch $final_path/doku.php
 # See https://www.dokuwiki.org/install:unused_files
 grep -Ev '^($|#)' ../sources/data/deleted.files | xargs -I {} sudo rm -vrf $final_path/{}
 
-# Files owned by root, www-data can just read
-find $final_path -type f -print0 | sudo xargs -0 chmod 0644
-find $final_path -type d -print0 | sudo xargs -0 chmod 0755
-sudo chown -R root: $final_path
+# Files owned by www-data can just read
+sudo find $final_path -type f -print0 | xargs -0 chmod 0644
+sudo find $final_path -type d -print0 | xargs -0 chmod 0755
+sudo chown -R www-data: $final_path
 
 # except for conf, data, some data subfolders, and lib/plugin, where www-data must have write permissions
 sudo chown -R www-data:root $final_path/{conf,data,data/attic,data/cache,data/index,data/locks,data/media*,data/meta,data/pages,data/tmp,lib/plugins,lib/tpl}