diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/Constants.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/Constants.kt
index 8eb7ee89b..702093120 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/Constants.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/Constants.kt
@@ -12,6 +12,7 @@ val EVENT_OCCURRENCE_TS = "event_occurrence_ts"
 val NEW_EVENT_START_TS = "new_event_start_ts"
 val WEEK_START_TIMESTAMP = "week_start_timestamp"
 val NEW_EVENT_SET_HOUR_DURATION = "new_event_set_hour_duration"
+val CALDAV = "Caldav"
 
 val MONTHLY_VIEW = 1
 val YEARLY_VIEW = 2
@@ -119,5 +120,5 @@ val FONT_SIZE_SMALL = 0
 val FONT_SIZE_MEDIUM = 1
 val FONT_SIZE_LARGE = 2
 
-val SOURCE_SIMPLE_CALENDAR = 0
-val SOURCE_IMPORTED_ICS = 2
+val SOURCE_SIMPLE_CALENDAR = "simple-calendar"
+val SOURCE_IMPORTED_ICS = "imported-ics"
diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/DBHelper.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/DBHelper.kt
index 0ab829093..25aad0e28 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/DBHelper.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/helpers/DBHelper.kt
@@ -35,7 +35,7 @@ class DBHelper private constructor(val context: Context) : SQLiteOpenHelper(cont
     private val COL_OFFSET = "offset"
     private val COL_IS_DST_INCLUDED = "is_dst_included"
     private val COL_LAST_UPDATED = "last_updated"
-    private val COL_SOURCE = "source"
+    private val COL_EVENT_SOURCE = "event_source"
 
     private val META_TABLE_NAME = "events_meta"
     private val COL_EVENT_ID = "event_id"
@@ -59,7 +59,7 @@ class DBHelper private constructor(val context: Context) : SQLiteOpenHelper(cont
     private val mDb: SQLiteDatabase = writableDatabase
 
     companion object {
-        private val DB_VERSION = 14
+        private val DB_VERSION = 15
         val DB_NAME = "events.db"
         val REGULAR_EVENT_TYPE_ID = 1
         var dbInstance: DBHelper? = null
@@ -79,7 +79,7 @@ class DBHelper private constructor(val context: Context) : SQLiteOpenHelper(cont
         db.execSQL("CREATE TABLE $MAIN_TABLE_NAME ($COL_ID INTEGER PRIMARY KEY AUTOINCREMENT, $COL_START_TS INTEGER, $COL_END_TS INTEGER, " +
                 "$COL_TITLE TEXT, $COL_DESCRIPTION TEXT, $COL_REMINDER_MINUTES INTEGER, $COL_REMINDER_MINUTES_2 INTEGER, $COL_REMINDER_MINUTES_3 INTEGER, " +
                 "$COL_IMPORT_ID TEXT, $COL_FLAGS INTEGER, $COL_EVENT_TYPE INTEGER NOT NULL DEFAULT $REGULAR_EVENT_TYPE_ID, " +
-                "$COL_PARENT_EVENT_ID INTEGER, $COL_OFFSET TEXT, $COL_IS_DST_INCLUDED INTEGER, $COL_LAST_UPDATED INTEGER, $COL_SOURCE INTEGER)")
+                "$COL_PARENT_EVENT_ID INTEGER, $COL_OFFSET TEXT, $COL_IS_DST_INCLUDED INTEGER, $COL_LAST_UPDATED INTEGER, $COL_EVENT_SOURCE TEXT)")
 
         createMetaTable(db)
         createTypesTable(db)
@@ -147,7 +147,10 @@ class DBHelper private constructor(val context: Context) : SQLiteOpenHelper(cont
 
         if (oldVersion < 14) {
             db.execSQL("ALTER TABLE $MAIN_TABLE_NAME ADD COLUMN $COL_LAST_UPDATED INTEGER NOT NULL DEFAULT 0")
-            db.execSQL("ALTER TABLE $MAIN_TABLE_NAME ADD COLUMN $COL_SOURCE INTEGER NOT NULL DEFAULT $SOURCE_SIMPLE_CALENDAR")
+        }
+
+        if (oldVersion < 15) {
+            db.execSQL("ALTER TABLE $MAIN_TABLE_NAME ADD COLUMN $COL_EVENT_SOURCE TEXT DEFAULT ''")
         }
     }
 
@@ -227,7 +230,7 @@ class DBHelper private constructor(val context: Context) : SQLiteOpenHelper(cont
             put(COL_OFFSET, event.offset)
             put(COL_IS_DST_INCLUDED, if (event.isDstIncluded) 1 else 0)
             put(COL_LAST_UPDATED, event.lastUpdated)
-            put(COL_SOURCE, event.source)
+            put(COL_EVENT_SOURCE, event.source)
         }
     }
 
@@ -663,7 +666,7 @@ class DBHelper private constructor(val context: Context) : SQLiteOpenHelper(cont
     private val allColumns: Array<String>
         get() = arrayOf("$MAIN_TABLE_NAME.$COL_ID", COL_START_TS, COL_END_TS, COL_TITLE, COL_DESCRIPTION, COL_REMINDER_MINUTES, COL_REMINDER_MINUTES_2,
                 COL_REMINDER_MINUTES_3, COL_REPEAT_INTERVAL, COL_REPEAT_RULE, COL_IMPORT_ID, COL_FLAGS, COL_REPEAT_LIMIT, COL_EVENT_TYPE, COL_OFFSET,
-                COL_IS_DST_INCLUDED, COL_LAST_UPDATED, COL_SOURCE)
+                COL_IS_DST_INCLUDED, COL_LAST_UPDATED, COL_EVENT_SOURCE)
 
     private fun fillEvents(cursor: Cursor?): List<Event> {
         val events = ArrayList<Event>()
@@ -687,7 +690,7 @@ class DBHelper private constructor(val context: Context) : SQLiteOpenHelper(cont
                     val offset = cursor.getStringValue(COL_OFFSET)
                     val isDstIncluded = cursor.getIntValue(COL_IS_DST_INCLUDED) == 1
                     val lastUpdated = cursor.getLongValue(COL_LAST_UPDATED)
-                    val source = cursor.getIntValue(COL_SOURCE)
+                    val source = cursor.getStringValue(COL_EVENT_SOURCE)
 
                     val ignoreEventOccurrences = if (repeatInterval != 0) {
                         getIgnoredOccurrences(id)
diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/models/Event.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/models/Event.kt
index d17fbf57e..930be5fe8 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/models/Event.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/models/Event.kt
@@ -12,7 +12,7 @@ data class Event(var id: Int = 0, var startTS: Int = 0, var endTS: Int = 0, var
                  var importId: String = "", var flags: Int = 0, var repeatLimit: Int = 0, var repeatRule: Int = 0,
                  var eventType: Int = DBHelper.REGULAR_EVENT_TYPE_ID, var ignoreEventOccurrences: ArrayList<Int> = ArrayList(),
                  var offset: String = "", var isDstIncluded: Boolean = false, var parentId: Int = 0, var lastUpdated: Long = 0L,
-                 var source: Int = SOURCE_SIMPLE_CALENDAR) : Serializable {
+                 var source: String = SOURCE_SIMPLE_CALENDAR) : Serializable {
 
     companion object {
         private val serialVersionUID = -32456795132345616L