diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/CalDAVEventsHandler.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/CalDAVEventsHandler.kt
index 5715fe97c..37d1e1262 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/CalDAVEventsHandler.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/CalDAVEventsHandler.kt
@@ -85,7 +85,7 @@ class CalDAVEventsHandler(val context: Context) {
 
                     if (endTS == 0) {
                         val duration = cursor.getStringValue(CalendarContract.Events.DURATION)
-                        endTS = startTS + Parser().parseDuration(duration)
+                        endTS = startTS + Parser().parseDurationSeconds(duration)
                     }
 
                     val importId = getCalDAVEventImportId(calendarId, id)
@@ -120,7 +120,6 @@ class CalDAVEventsHandler(val context: Context) {
     }
 
     fun addCalDAVEvent(event: Event, calendarId: Long) {
-        val durationMinutes = (event.endTS - event.startTS) / 1000 / 60
         val uri = CalendarContract.Events.CONTENT_URI
         val values = ContentValues().apply {
             put(CalendarContract.Events.CALENDAR_ID, calendarId)
@@ -128,14 +127,14 @@ class CalDAVEventsHandler(val context: Context) {
             put(CalendarContract.Events.DESCRIPTION, event.description)
             put(CalendarContract.Events.DTSTART, event.startTS * 1000L)
             put(CalendarContract.Events.ALL_DAY, if (event.getIsAllDay()) 1 else 0)
-            put(CalendarContract.Events.RRULE, Parser().getShortRepeatInterval(event))
+            put(CalendarContract.Events.RRULE, Parser().getRepeatCode(event))
             put(CalendarContract.Events.EVENT_TIMEZONE, TimeZone.getDefault().toString())
 
             if (event.getIsAllDay() && event.endTS > event.startTS)
                 event.endTS += DAY
 
             if (event.repeatInterval > 0) {
-                put(CalendarContract.Events.DURATION, Parser().getDurationString(durationMinutes))
+                put(CalendarContract.Events.DURATION, getDurationCode(event))
             } else {
                 put(CalendarContract.Events.DTEND, event.endTS * 1000L)
             }
@@ -148,6 +147,15 @@ class CalDAVEventsHandler(val context: Context) {
         context.dbHelper.updateEventImportIdAndSource(event.id, importId, "$CALDAV-$calendarId")
     }
 
+    private fun getDurationCode(event: Event): String {
+        return if (event.getIsAllDay()) {
+            val dur = Math.max(1, (event.endTS - event.startTS) / DAY)
+            "P${dur}D"
+        } else {
+            Parser().getDurationCode((event.endTS - event.startTS) / 60)
+        }
+    }
+
     fun getCalDAVEventReminders(eventId: Long): List<Int> {
         val reminders = ArrayList<Int>()
         val uri = CalendarContract.Reminders.CONTENT_URI
diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/IcsExporter.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/IcsExporter.kt
index 845155f9a..d64b69e3b 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/IcsExporter.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/IcsExporter.kt
@@ -38,7 +38,7 @@ class IcsExporter {
                     }
 
                     out.writeLn("$STATUS$CONFIRMED")
-                    Parser().getShortRepeatInterval(event).let { if (it.isNotEmpty()) out.writeLn("$RRULE$it") }
+                    Parser().getRepeatCode(event).let { if (it.isNotEmpty()) out.writeLn("$RRULE$it") }
 
                     fillReminders(event, out)
                     fillIgnoredOccurrences(event, out)
@@ -69,7 +69,7 @@ class IcsExporter {
         if (minutes != -1) {
             out.writeLn(BEGIN_ALARM)
             out.writeLn("$ACTION$DISPLAY")
-            out.writeLn("$TRIGGER${Parser().getDurationString(minutes)}")
+            out.writeLn("$TRIGGER-${Parser().getDurationCode(minutes)}")
             out.writeLn(END_ALARM)
         }
     }
diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/IcsImporter.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/IcsImporter.kt
index bcf56ab54..16341a4ae 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/IcsImporter.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/IcsImporter.kt
@@ -63,7 +63,7 @@ class IcsImporter {
                         curEnd = getTimestamp(line.substring(DTEND.length))
                     } else if (line.startsWith(DURATION)) {
                         val duration = line.substring(DURATION.length)
-                        curEnd = curStart + Parser().parseDuration(duration)
+                        curEnd = curStart + Parser().parseDurationSeconds(duration)
                     } else if (line.startsWith(SUMMARY) && !isNotificationDescription) {
                         curTitle = line.substring(SUMMARY.length)
                         curTitle = getTitle(curTitle).replace("\\n", "\n")
@@ -81,7 +81,7 @@ class IcsImporter {
                         lastReminderAction = line.substring(ACTION.length)
                     } else if (line.startsWith(TRIGGER)) {
                         if (lastReminderAction == DISPLAY)
-                            curReminderMinutes.add(Parser().parseDuration(line.substring(TRIGGER.length)) / 60)
+                            curReminderMinutes.add(Parser().parseDurationSeconds(line.substring(TRIGGER.length)) / 60)
                     } else if (line.startsWith(CATEGORIES)) {
                         val categories = line.substring(CATEGORIES.length)
                         tryAddCategories(categories, context)
diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/Parser.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/Parser.kt
index a71d506cd..d78a5f61a 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/Parser.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/Parser.kt
@@ -50,14 +50,12 @@ class Parser {
         return RepeatRule(repeatInterval, repeatRule, repeatLimit)
     }
 
-    private fun getFrequencySeconds(interval: String): Int {
-        return when (interval) {
-            DAILY -> DAY
-            WEEKLY -> WEEK
-            MONTHLY -> MONTH
-            YEARLY -> YEAR
-            else -> 0
-        }
+    private fun getFrequencySeconds(interval: String) = when (interval) {
+        DAILY -> DAY
+        WEEKLY -> WEEK
+        MONTHLY -> MONTH
+        YEARLY -> YEAR
+        else -> 0
     }
 
     private fun handleRepeatRule(value: String): Int {
@@ -96,7 +94,7 @@ class Parser {
     }
 
     // from Daily, 5x... to RRULE:FREQ=DAILY;COUNT=5
-    fun getShortRepeatInterval(event: Event): String {
+    fun getRepeatCode(event: Event): String {
         val repeatInterval = event.repeatInterval
         if (repeatInterval == 0)
             return ""
@@ -108,35 +106,24 @@ class Parser {
         return "$FREQ=$freq;$INTERVAL=$interval$repeatLimit$byDay"
     }
 
-    private fun getFreq(interval: Int): String {
-        return if (interval % YEAR == 0)
-            YEARLY
-        else if (interval % MONTH == 0)
-            MONTHLY
-        else if (interval % WEEK == 0)
-            WEEKLY
-        else
-            DAILY
+    private fun getFreq(interval: Int) = when {
+        interval % YEAR == 0 -> YEARLY
+        interval % MONTH == 0 -> MONTHLY
+        interval % WEEK == 0 -> WEEKLY
+        else -> DAILY
     }
 
-    private fun getInterval(interval: Int): Int {
-        return if (interval % YEAR == 0)
-            interval / YEAR
-        else if (interval % MONTH == 0)
-            interval / MONTH
-        else if (interval % WEEK == 0)
-            interval / WEEK
-        else
-            interval / DAY
+    private fun getInterval(interval: Int) = when {
+        interval % YEAR == 0 -> interval / YEAR
+        interval % MONTH == 0 -> interval / MONTH
+        interval % WEEK == 0 -> interval / WEEK
+        else -> interval / DAY
     }
 
-    private fun getRepeatLimitString(event: Event): String {
-        return if (event.repeatLimit == 0)
-            ""
-        else if (event.repeatLimit < 0)
-            ";$COUNT=${-event.repeatLimit}"
-        else
-            ";$UNTIL=${Formatter.getDayCodeFromTS(event.repeatLimit)}"
+    private fun getRepeatLimitString(event: Event) = when {
+        event.repeatLimit == 0 -> ""
+        event.repeatLimit < 0 -> ";$COUNT=${-event.repeatLimit}"
+        else -> ";$UNTIL=${Formatter.getDayCodeFromTS(event.repeatLimit)}"
     }
 
     private fun getByDay(event: Event): String {
@@ -179,22 +166,20 @@ class Parser {
         return result.trimEnd(',')
     }
 
-    private fun getDayLetters(dayOfWeek: Int): String {
-        return when (dayOfWeek) {
-            1 -> MO
-            2 -> TU
-            3 -> WE
-            4 -> TH
-            5 -> FR
-            6 -> SA
-            else -> SU
-        }
+    private fun getDayLetters(dayOfWeek: Int) = when (dayOfWeek) {
+        1 -> MO
+        2 -> TU
+        3 -> WE
+        4 -> TH
+        5 -> FR
+        6 -> SA
+        else -> SU
     }
 
     // from P0DT1H5M0S to 3900 (seconds)
-    fun parseDuration(duration: String): Int {
+    fun parseDurationSeconds(duration: String): Int {
         val weeks = getDurationValue(duration, "W")
-        val days = getDurationValue(duration, "DT")
+        val days = getDurationValue(duration, "D")
         val hours = getDurationValue(duration, "H")
         val minutes = getDurationValue(duration, "M")
         val seconds = getDurationValue(duration, "S")
@@ -210,7 +195,7 @@ class Parser {
     private fun getDurationValue(duration: String, char: String) = Regex("[0-9]+(?=$char)").find(duration)?.value?.toInt() ?: 0
 
     // from 65 to P0DT1H5M0S
-    fun getDurationString(minutes: Int): String {
+    fun getDurationCode(minutes: Int): String {
         var days = 0
         var hours = 0
         var remainder = minutes
@@ -222,6 +207,6 @@ class Parser {
             hours = Math.floor((remainder / 60).toDouble()).toInt()
             remainder -= hours * 60
         }
-        return "-P${days}DT${hours}H${remainder}M0S"
+        return "P${days}DT${hours}H${remainder}M0S"
     }
 }