diff --git a/scripts/_common.sh b/scripts/_common.sh
index 3924433..1b0062a 100644
--- a/scripts/_common.sh
+++ b/scripts/_common.sh
@@ -16,7 +16,7 @@ _get_metronome_config_dir() {
 
     # multi_instance=false, there's only one
     metronome_app=$(yunohost app list --json | jq -r '.apps[] | select(.id == "metronome") | .id')
-    if (( ${#metronome_apps[@]} == 0 )); then
+    if [[ -z "${metronome_app:-}" ]]; then
         ynh_print_warn --message="Could not find any metronome app!"
         return 1
     fi