diff --git a/modoboa/core/app_settings.py b/modoboa/core/app_settings.py
index 66f1d0c59..13977a3b1 100644
--- a/modoboa/core/app_settings.py
+++ b/modoboa/core/app_settings.py
@@ -200,7 +200,7 @@ class GeneralParametersForm(parameters.AdminParametersForm):
     top_notifications_check_interval = forms.IntegerField(
         label=_("Top notifications check interval"),
         initial=30,
-        help_text=_("Interval between two top notification checks"),
+        help_text=_("Interval between two top notification checks (in seconds)"),
         widget=forms.TextInput(attrs={"class": "form-control"})
     )