diff --git a/lib/Component/VAlarm.php b/lib/Component/VAlarm.php
index 3e5797b0..abe61768 100644
--- a/lib/Component/VAlarm.php
+++ b/lib/Component/VAlarm.php
@@ -39,13 +39,7 @@ public function getEffectiveTriggerTime(): \DateTimeImmutable
             /** @var VEvent|VTodo $parentComponent */
             $parentComponent = $this->parent;
             if ('START' === $related) {
-                if ('VTODO' === $parentComponent->name) {
-                    $propName = 'DUE';
-                } else {
-                    $propName = 'DTSTART';
-                }
-
-                $effectiveTrigger = $parentComponent->$propName->getDateTime();
+                $effectiveTrigger = $parentComponent->DTSTART->getDateTime();
             } else {
                 if ('VTODO' === $parentComponent->name) {
                     $endProp = 'DUE';
diff --git a/tests/VObject/Component/VAlarmTest.php b/tests/VObject/Component/VAlarmTest.php
index 4694d636..a67991ff 100644
--- a/tests/VObject/Component/VAlarmTest.php
+++ b/tests/VObject/Component/VAlarmTest.php
@@ -123,6 +123,19 @@ public function timeRangeTestData(): array
         $tests[] = [$valarm7, new \DateTime('2012-02-25 01:00:00'), new \DateTime('2012-03-05 01:00:00'), true];
         $tests[] = [$valarm7, new \DateTime('2012-03-25 01:00:00'), new \DateTime('2012-04-05 01:00:00'), false];
 
+        // Relation to start time of todo
+        $valarm8 = $calendar->createComponent('VALARM');
+        $valarm8->TRIGGER = '-P1D';
+        $valarm8->TRIGGER['VALUE'] = 'DURATION';
+
+        $vtodo8 = $calendar->createComponent('VTODO');
+        $vtodo8->DTSTART = '20120301T130000Z';
+        $vtodo8->DUE = '20120401T130000Z';
+        $vtodo8->add($valarm8);
+
+        $tests[] = [$valarm8, new \DateTime('2012-02-25 01:00:00'), new \DateTime('2012-03-05 01:00:00'), true];
+        $tests[] = [$valarm8, new \DateTime('2012-03-25 01:00:00'), new \DateTime('2012-04-05 01:00:00'), false];
+
         return $tests;
     }
 
@@ -151,7 +164,7 @@ public function testInTimeRangeBuggy(): void
 DTSTAMP:20121003T064931Z
 UID:b848cb9a7bb16e464a06c222ca1f8102@examle.com
 STATUS:NEEDS-ACTION
-DUE:20121005T000000Z
+DTSTART:20121005T000000Z
 SUMMARY:Task 1
 CATEGORIES:AlarmCategory
 BEGIN:VALARM