diff --git a/app/src/main/java/org/tasks/data/MyAndroidTask.kt b/app/src/main/java/org/tasks/data/MyAndroidTask.kt
index f1cfcd2e5..1c0f80ccd 100644
--- a/app/src/main/java/org/tasks/data/MyAndroidTask.kt
+++ b/app/src/main/java/org/tasks/data/MyAndroidTask.kt
@@ -3,15 +3,14 @@ package org.tasks.data
 import android.content.ContentUris
 import android.database.Cursor
 import android.net.Uri
-import at.bitfire.ical4android.AndroidTask
 import at.bitfire.ical4android.BatchOperation
 import at.bitfire.ical4android.BatchOperation.CpoBuilder.Companion.newInsert
 import at.bitfire.ical4android.BatchOperation.CpoBuilder.Companion.newUpdate
+import at.bitfire.ical4android.DmfsTask
 import at.bitfire.ical4android.ICalendar
-import at.bitfire.ical4android.Ical4Android
 import at.bitfire.ical4android.Task
 import at.bitfire.ical4android.UnknownProperty
-import at.bitfire.ical4android.util.MiscUtils.CursorHelper.toValues
+import at.bitfire.ical4android.util.MiscUtils.toValues
 import net.fortuna.ical4j.model.Parameter
 import net.fortuna.ical4j.model.parameter.RelType
 import net.fortuna.ical4j.model.parameter.Related
@@ -21,7 +20,7 @@ import org.tasks.data.OpenTaskDao.Companion.getLong
 import java.util.Locale
 import java.util.logging.Level
 
-class MyAndroidTask() : AndroidTask(null) {
+class MyAndroidTask() : DmfsTask(null) {
 
     constructor(cursor: Cursor) : this() {
         val values = cursor.toValues()
@@ -99,7 +98,7 @@ class MyAndroidTask() : AndroidTask(null) {
                     .withValue(TaskContract.Property.Alarm.MESSAGE, alarm.description?.value ?: alarm.summary)
                     .withValue(TaskContract.Property.Alarm.ALARM_TYPE, alarmType)
 
-            Ical4Android.log.log(Level.FINE, "Inserting alarm", builder.build())
+            logger.log(Level.FINE, "Inserting alarm", builder.build())
             batch.add(builder)
         }
     }
@@ -110,7 +109,7 @@ class MyAndroidTask() : AndroidTask(null) {
                     .withTaskId(TaskContract.Property.Category.TASK_ID, idxTask)
                     .withValue(TaskContract.Property.Category.MIMETYPE, TaskContract.Property.Category.CONTENT_ITEM_TYPE)
                     .withValue(TaskContract.Property.Category.CATEGORY_NAME, category)
-            Ical4Android.log.log(Level.FINE, "Inserting category", builder.build())
+            logger.log(Level.FINE, "Inserting category", builder.build())
             batch.add(builder)
         }
     }
@@ -130,7 +129,7 @@ class MyAndroidTask() : AndroidTask(null) {
                     .withValue(TaskContract.Property.Relation.MIMETYPE, TaskContract.Property.Relation.CONTENT_ITEM_TYPE)
                     .withValue(TaskContract.Property.Relation.RELATED_UID, relatedTo.value)
                     .withValue(TaskContract.Property.Relation.RELATED_TYPE, relType)
-            Ical4Android.log.log(Level.FINE, "Inserting relation", builder.build())
+            logger.log(Level.FINE, "Inserting relation", builder.build())
             batch.add(builder)
         }
     }
@@ -138,7 +137,7 @@ class MyAndroidTask() : AndroidTask(null) {
     private fun insertUnknownProperties(batch: MutableList<BatchOperation.CpoBuilder>, idxTask: Int?, uri: Uri) {
         for (property in requireNotNull(task).unknownProperties) {
             if (property.value.length > UnknownProperty.MAX_UNKNOWN_PROPERTY_SIZE) {
-                Ical4Android.log.warning("Ignoring unknown property with ${property.value.length} octets (too long)")
+                logger.warning("Ignoring unknown property with ${property.value.length} octets (too long)")
                 return
             }
 
@@ -146,8 +145,8 @@ class MyAndroidTask() : AndroidTask(null) {
                     .withTaskId(TaskContract.Properties.TASK_ID, idxTask)
                     .withValue(TaskContract.Properties.MIMETYPE, UnknownProperty.CONTENT_ITEM_TYPE)
                     .withValue(UNKNOWN_PROPERTY_DATA, UnknownProperty.toJsonString(property))
-            Ical4Android.log.log(Level.FINE, "Inserting unknown property", builder.build())
+            logger.log(Level.FINE, "Inserting unknown property", builder.build())
             batch.add(builder)
         }
     }
-}
\ No newline at end of file
+}
diff --git a/app/src/test/java/org/tasks/caldav/extensions/VAlarmTests.kt b/app/src/test/java/org/tasks/caldav/extensions/VAlarmTests.kt
index 38d1f54f5..ba9991205 100644
--- a/app/src/test/java/org/tasks/caldav/extensions/VAlarmTests.kt
+++ b/app/src/test/java/org/tasks/caldav/extensions/VAlarmTests.kt
@@ -1,13 +1,19 @@
 package org.tasks.caldav.extensions
 
+import at.bitfire.ical4android.Task.Companion.tasksFromReader
 import org.junit.Assert.assertEquals
 import org.junit.Test
+import org.tasks.caldav.iCalendar.Companion.applyLocal
+import org.tasks.data.createDueDate
 import org.tasks.data.entity.Alarm
 import org.tasks.data.entity.Alarm.Companion.TYPE_DATE_TIME
 import org.tasks.data.entity.Alarm.Companion.TYPE_REL_END
 import org.tasks.data.entity.Alarm.Companion.TYPE_REL_START
+import org.tasks.data.entity.CaldavTask
+import org.tasks.data.entity.Task
 import org.tasks.time.DateTime
 import org.tasks.time.DateTime.Companion.UTC
+import java.io.ByteArrayInputStream
 import java.util.concurrent.TimeUnit.HOURS
 import java.util.concurrent.TimeUnit.MINUTES
 
@@ -111,4 +117,34 @@ class VAlarmTests {
         )
         assertEquals(alarm, alarm.toVAlarm()?.toAlarm())
     }
-}
\ No newline at end of file
+
+    @Test
+    fun serializeAlarms() {
+        val remoteTask = at.bitfire.ical4android.Task()
+        remoteTask.applyLocal(
+            CaldavTask(
+                calendar = "",
+            ),
+            Task(
+                dueDate = createDueDate(
+                    Task.URGENCY_SPECIFIC_DAY_TIME,
+                    DateTime(2025, 9, 4, 18, 0, 0).millis
+                ),
+            ),
+        )
+        Alarm(time = 0, type = TYPE_REL_END).toVAlarm()?.let { remoteTask.alarms.add(it) }
+
+        val os = java.io.ByteArrayOutputStream()
+        remoteTask.write(os)
+
+        val tasks = tasksFromReader(ByteArrayInputStream(os.toByteArray()).reader())
+        assertEquals(1, tasks.size)
+
+        val task = tasks.first()
+        assertEquals(1, task.alarms.size)
+
+        val alarm = task.alarms.first().toAlarm()
+        assertEquals(TYPE_REL_END, alarm?.type)
+        assertEquals(0L, alarm?.time)
+    }
+}
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 7b010445b..f24974d68 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -27,7 +27,7 @@ google-services = "4.4.3"
 grpc = "1.73.0"
 hilt = "1.2.0"
 horologist = "0.7.15"
-ical4android = "2fe63dd"
+ical4android = "fcb0311ca7"
 jchronic = "0.2.6"
 jems = "1.33"
 junit-junit = "4.13.2"