diff --git a/manifest.json b/manifest.json
index 88cd0aa..de41371 100644
--- a/manifest.json
+++ b/manifest.json
@@ -6,7 +6,7 @@
         "en": "Distributed and RESTful search engine",
         "fr": "Moteur de recherche RESTful"
     },
-    "version": "7.17.8~ynh4",
+    "version": "7.17.8~ynh5",
     "url": "https://github.com/elastic/elasticsearch",
     "upstream": {
         "license": "SSPL-1.0",
diff --git a/scripts/install b/scripts/install
index dfb0fca..be490c4 100755
--- a/scripts/install
+++ b/scripts/install
@@ -116,7 +116,7 @@ ynh_script_progression --message="Increasing maximum map count (sysctl)..."
 # Increase the maximum number of files inotify can monitor.
 cp -a ../conf/90-max_map_count-elasticsearch.conf /etc/sysctl.d/
 # Then, reload the kernel configuration.
-if ! [ "$container" = "lxc" ] # lxc doesn't allow sysctl to play with kernel options.
+if ! [ "${container:-}" = "lxc" ] # lxc doesn't allow sysctl to play with kernel options.
 then
 	sysctl -p /etc/sysctl.d/90-max_map_count-elasticsearch.conf
 fi
diff --git a/scripts/remove b/scripts/remove
index d38411c..18b9aeb 100755
--- a/scripts/remove
+++ b/scripts/remove
@@ -105,7 +105,7 @@ ynh_script_progression --message="Removing various files..."
 if [ -e "/etc/sysctl.d/90-max_map_count-elasticsearch.conf" ]; then
 	ynh_secure_remove --file="/etc/sysctl.d/90-max_map_count-elasticsearch.conf"
 	# Reload the kernel configuration.
-	if ! [ "$container" = "lxc" ] # lxc doesn't allow sysctl to play with kernel options.
+	if ! [ "${container:-}" = "lxc" ] # lxc doesn't allow sysctl to play with kernel options.
 	then
 		sysctl --system
 	fi
diff --git a/scripts/restore b/scripts/restore
index e9359ab..28e18d5 100755
--- a/scripts/restore
+++ b/scripts/restore
@@ -91,7 +91,7 @@ chown $app:$app "/run/$app"
 ynh_script_progression --message="Restoring various files..."
 
 ynh_restore_file --origin_path="/etc/sysctl.d/90-max_map_count-elasticsearch.conf"
-if ! [ "$container" = "lxc" ] # lxc doesn't allow sysctl to play with kernel options.
+if ! [ "${container:-}" = "lxc" ] # lxc doesn't allow sysctl to play with kernel options.
 then
 	sysctl -p /etc/sysctl.d/90-max_map_count-elasticsearch.conf
 fi
diff --git a/scripts/upgrade b/scripts/upgrade
index 5c8e10f..0e6c27e 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -99,7 +99,7 @@ ynh_script_progression --message="Increasing maximum map count (sysctl)..."
 # Increase the maximum number of files inotify can monitor.
 cp -a ../conf/90-max_map_count-elasticsearch.conf /etc/sysctl.d/
 # Then, reload the kernel configuration.
-if ! [ "$container" = "lxc" ] # lxc doesn't allow sysctl to play with kernel options.
+if ! [ "${container:-}" = "lxc" ] # lxc doesn't allow sysctl to play with kernel options.
 then
 	sysctl -p /etc/sysctl.d/90-max_map_count-elasticsearch.conf
 fi