diff --git a/larigira/timeform_frequency.py b/larigira/timeform_frequency.py
index 85efbf3..f0d09fd 100644
--- a/larigira/timeform_frequency.py
+++ b/larigira/timeform_frequency.py
@@ -9,18 +9,20 @@ from wtforms import StringField, DateTimeField, validators, \
 class FrequencyAlarmForm(Form):
     nick = StringField('Alarm nick', validators=[validators.required()],
                        description='A simple name to recognize this alarm')
-    start = DateTimeField('Start date and time',
-                          validators=[validators.required()],
-                          description='Date before which no alarm will ring, '
-                          'expressed as YYYY-MM-DD HH:MM:SS')
-    end = DateTimeField('End date and time',
-                        validators=[validators.optional()],
-                        description='Date after which no alarm will ring, '
-                        'expressed as YYYY-MM-DD HH:MM:SS')
     interval = StringField('Frequency',
                            validators=[validators.required()],
                            description='in seconds, or human-readable '
                            '(like 9w3d12h)')
+    start = DateTimeField('Start date and time',
+                          validators=[validators.optional()],
+                          description='Date before which no alarm will ring, '
+                          'expressed as YYYY-MM-DD HH:MM:SS; if omitted, the '
+                          'alarm will always ring')
+    end = DateTimeField('End date and time',
+                        validators=[validators.optional()],
+                        description='Date after which no alarm will ring, '
+                        'expressed as YYYY-MM-DD HH:MM:SS; if omitted, the '
+                        'alarm will always ring')
     submit = SubmitField('Submit')
 
     def populate_from_timespec(self, timespec):
@@ -46,9 +48,12 @@ def frequencyalarm_receive(form):
     obj = {
         'kind': 'frequency',
         'nick': form.nick.data,
-        'start': int(form.start.data.strftime('%s')),
         'interval': form.interval.data,
     }
+    if form.start.data:
+        obj['start'] = int(form.end.data.strftime('%s'))
+    else:
+        obj['start'] = 0
     if form.end.data:
         obj['end'] = int(form.end.data.strftime('%s'))
     return obj