diff --git a/scripts/backup b/scripts/backup
index f237759..4693a0b 100755
--- a/scripts/backup
+++ b/scripts/backup
@@ -43,7 +43,7 @@ ynh_backup --src_path="/etc/sudoers.d/$app"
 # BACKUP THE IMPORTER PLUGIN POST APP INSTALL HOOK
 #=================================================
 
-ynh_backup --src_path="/etc/yunohost/hooks.d/post_app_install/$app_sync_app_importer.sh"
+ynh_backup --src_path="/etc/yunohost/hooks.d/post_app_install/${app}_sync_app_importer.sh"
 
 #=================================================
 # BACKUP THE MYSQL DATABASE
diff --git a/scripts/install b/scripts/install
index 3373916..1645950 100755
--- a/scripts/install
+++ b/scripts/install
@@ -17,7 +17,7 @@ ynh_script_progression --message="Setting up source files..." --weight=5
 # Download, check integrity, uncompress and patch the source from app.src
 ynh_setup_source --dest_dir="$install_dir"
 
-chown -R $app:www-data $install_dir
+chown -R ${app}:www-data $install_dir
 chmod -R u=rwX,g=rX,o-rwx $install_dir
 
 #=================================================
@@ -103,9 +103,9 @@ ynh_add_config --template="sudoers" --destination="/etc/sudoers.d/$app"
 chown root:root /etc/sudoers.d/$app
 
 # Add a post app install hook to sync the app importer
-ynh_add_config --template="sync_app_importer.sh" --destination="/etc/yunohost/hooks.d/post_app_install/$app_sync_app_importer.sh"
-chown root:root /etc/yunohost/hooks.d/post_app_install/$app_sync_app_importer.sh
-chmod +x /etc/yunohost/hooks.d/post_app_install/$app_sync_app_importer.sh
+ynh_add_config --template="sync_app_importer.sh" --destination="/etc/yunohost/hooks.d/post_app_install/${app}_sync_app_importer.sh"
+chown root:root /etc/yunohost/hooks.d/post_app_install/${app}_sync_app_importer.sh
+chmod +x /etc/yunohost/hooks.d/post_app_install/${app}_sync_app_importer.sh
 
 # At last, run the YunoHost app importer
 ynh_script_progression --message="Import YunoHost apps in bazar" --weight=2
@@ -146,7 +146,7 @@ fi
 # SECURE FILES AND DIRECTORIES
 #=================================================
 
-chown -R $app:www-data $install_dir
+chown -R ${app}:www-data $install_dir
 chmod -R u=rwX,g=rX,o-rwx $install_dir
 chmod g-rwx $install_dir/wakka.config.php
 
diff --git a/scripts/remove b/scripts/remove
index dce13b4..db4d6eb 100755
--- a/scripts/remove
+++ b/scripts/remove
@@ -24,7 +24,7 @@ ynh_remove_fpm_config
 ynh_secure_remove --file="/etc/sudoers/$app"
 
 # Remove post app install hook
-ynh_secure_remove --file="/etc/yunohost/hooks.d/post_app_install/$app_sync_app_importer.sh"
+ynh_secure_remove --file="/etc/yunohost/hooks.d/post_app_install/${app}_sync_app_importer.sh"
 
 #=================================================
 # END OF SCRIPT
diff --git a/scripts/restore b/scripts/restore
index 87d2b2d..d50e58d 100755
--- a/scripts/restore
+++ b/scripts/restore
@@ -47,7 +47,7 @@ ynh_restore_file --origin_path="/etc/sudoers.d/$app"
 #=================================================
 ynh_script_progression --message="Restoring the app importer post app install hook..."
 
-ynh_restore_file --origin_path="/etc/yunohost/hooks.d/post_app_install/$app_sync_app_importer.sh"
+ynh_restore_file --origin_path="/etc/yunohost/hooks.d/post_app_install/${app}_sync_app_importer.sh"
 
 #=================================================
 # RESTORE THE MYSQL DATABASE
diff --git a/scripts/upgrade b/scripts/upgrade
index 6c1a048..1f794e5 100755
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -35,7 +35,7 @@ if [ "$upgrade_type" == "UPGRADE_APP" ]; then
 fi
 
 chmod -R o-rwx "$install_dir"
-chown -R $app:www-data "$install_dir"
+chown -R ${app}:www-data "$install_dir"
 
 #=================================================
 # PHP-FPM CONFIGURATION
@@ -81,9 +81,9 @@ ynh_add_config --template="sudoers" --destination="/etc/sudoers.d/$app"
 chown root:root /etc/sudoers.d/$app
 
 # Add a post app install hook to sync the app importer
-ynh_add_config --template="sync_app_importer.sh" --destination="/etc/yunohost/hooks.d/post_app_install/$app_sync_app_importer.sh"
-chown root:root /etc/yunohost/hooks.d/post_app_install/$app_sync_app_importer.sh
-chmod +x /etc/yunohost/hooks.d/post_app_install/$app_sync_app_importer.sh
+ynh_add_config --template="sync_app_importer.sh" --destination="/etc/yunohost/hooks.d/post_app_install/${app}_sync_app_importer.sh"
+chown root:root /etc/yunohost/hooks.d/post_app_install/${app}_sync_app_importer.sh
+chmod +x /etc/yunohost/hooks.d/post_app_install/${app}_sync_app_importer.sh
 
 # ToDo : Add importer config in wakka.config.php if it is not already there ?
 # if [ ??? ]; then
@@ -100,7 +100,7 @@ popd
 # SECURE FILES AND DIRECTORIES
 #=================================================
 
-chown -R $app:www-data $install_dir
+chown -R ${app}:www-data $install_dir
 chmod -R u=rwX,g=rX,o-rwx $install_dir
 chmod g-rwx $install_dir/wakka.config.php