diff --git a/src/recurrence.cpp b/src/recurrence.cpp
--- a/src/recurrence.cpp
+++ b/src/recurrence.cpp
@@ -24,6 +24,7 @@
 #include "recurrence.h"
 #include "sortablelist.h"
 #include "utils.h"
+#include "recurrencehelper_p.h"
 
 #include "kcalcore_debug.h"
 
@@ -443,7 +444,7 @@
         }
         dts << rl;
     }
-    dts.sortUnique();
+    sortAndRemoveDuplicates(dts);
     return dts.isEmpty() ? QDateTime() : dts.last();
 }
 
@@ -873,11 +874,11 @@
         return;
     }
 
-    SortableList<int> mD(monthlyDays);
-    SortableList<int> rbD(rrule->byMonthDays());
+    QList<int> mD(monthlyDays);
+    QList<int> rbD(rrule->byMonthDays());
 
-    mD.sortUnique();
-    rbD.sortUnique();
+    sortAndRemoveDuplicates(mD);
+    sortAndRemoveDuplicates(rbD);
 
     if (mD != rbD) {
         rrule->setByMonthDays(monthlyDays);
@@ -914,11 +915,11 @@
         return;
     }
 
-    SortableList<int> d(days);
-    SortableList<int> bYD(rrule->byYearDays());
+    QList<int> d(days);
+    QList<int> bYD(rrule->byYearDays());
 
-    d.sortUnique();
-    bYD.sortUnique();
+    sortAndRemoveDuplicates(d);
+    sortAndRemoveDuplicates(bYD);
 
     if (d != bYD) {
         rrule->setByYearDays(days);
@@ -978,11 +979,11 @@
         return;
     }
 
-    SortableList<int> m(months);
-    SortableList<int> bM(rrule->byMonths());
+    QList<int> m(months);
+    QList<int> bM(rrule->byMonths());
 
-    m.sortUnique();
-    bM.sortUnique();
+    sortAndRemoveDuplicates(m);
+    sortAndRemoveDuplicates(bM);
 
     if (m != bM) {
         rrule->setByMonths(months);
@@ -1029,7 +1030,7 @@
     for (i = 0, end = d->mRRules.count();  i < end;  ++i) {
         times += d->mRRules[i]->recurTimesOn(date, timeZone);
     }
-    times.sortUnique();
+    sortAndRemoveDuplicates(times);
 
     foundDate = false;
     TimeList extimes;
@@ -1047,7 +1048,7 @@
             extimes += d->mExRules[i]->recurTimesOn(date, timeZone);
         }
     }
-    extimes.sortUnique();
+    sortAndRemoveDuplicates(extimes);
 
     int st = 0;
     for (i = 0, end = extimes.count();  i < end;  ++i) {
@@ -1095,7 +1096,7 @@
         times += d->mStartDateTime;
     }
 
-    times.sortUnique();
+    sortAndRemoveDuplicates(times);
 
     // Remove excluded times
     int idt = 0;
@@ -1114,7 +1115,7 @@
         extimes += d->mExRules[i]->timesInInterval(start, end);
     }
     extimes += d->mExDateTimes;
-    extimes.sortUnique();
+    sortAndRemoveDuplicates(extimes);
 
     int st = 0;
     for (i = 0, count = extimes.count();  i < count;  ++i) {
@@ -1179,7 +1180,7 @@
         }
 
         // Take the first of these (all others can't be used later on)
-        dates.sortUnique();
+        sortAndRemoveDuplicates(dates);
         if (dates.isEmpty()) {
             return QDateTime();
         }
@@ -1250,7 +1251,7 @@
         }
 
         // Take the last of these (all others can't be used later on)
-        dates.sortUnique();
+        sortAndRemoveDuplicates(dates);
         if (dates.isEmpty()) {
             return QDateTime();
         }
@@ -1365,7 +1366,7 @@
     }
 
     d->mRDateTimes = rdates;
-    d->mRDateTimes.sortUnique();
+    sortAndRemoveDuplicates(d->mRDateTimes);
     updated();
 }
 
@@ -1391,7 +1392,7 @@
     }
 
     d->mRDates = rdates;
-    d->mRDates.sortUnique();
+    sortAndRemoveDuplicates(d->mRDates);
     updated();
 }
 
@@ -1417,7 +1418,7 @@
     }
 
     d->mExDateTimes = exdates;
-    d->mExDateTimes.sortUnique();
+    sortAndRemoveDuplicates(d->mExDateTimes);
 }
 
 void Recurrence::addExDateTime(const QDateTime &exdate)
@@ -1442,7 +1443,7 @@
     }
 
     DateList l = exdates;
-    l.sortUnique();
+    sortAndRemoveDuplicates(l);
 
     if (d->mExDates != l) {
         d->mExDates = l;
diff --git a/src/recurrencehelper_p.h b/src/recurrencehelper_p.h
new file mode 100644
--- /dev/null
+++ b/src/recurrencehelper_p.h
@@ -0,0 +1,38 @@
+/*
+  This file is part of the kcalcore library.
+
+  Copyright (c) 2019 Volker Krause <vkrause@kde.org>
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Library General Public
+  License as published by the Free Software Foundation; either
+  version 2 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Library General Public License for more details.
+
+  You should have received a copy of the GNU Library General Public License
+  along with this library; see the file COPYING.LIB.  If not, write to
+  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+  Boston, MA 02110-1301, USA.
+*/
+
+#ifndef KCALCORE_RECURRENCEHELPER_H
+#define KCALCORE_RECURRENCEHELPER_H
+
+#include <algorithm>
+
+namespace KCalCore {
+
+template <typename T>
+inline void sortAndRemoveDuplicates(T &container)
+{
+    std::sort(container.begin(), container.end());
+    container.erase(std::unique(container.begin(), container.end()));
+}
+
+}
+
+#endif
diff --git a/src/recurrencerule.cpp b/src/recurrencerule.cpp
--- a/src/recurrencerule.cpp
+++ b/src/recurrencerule.cpp
@@ -22,6 +22,7 @@
 #include "recurrencerule.h"
 #include "utils.h"
 #include "kcalcore_debug.h"
+#include "recurrencehelper_p.h"
 
 #include <QStringList>
 #include <QTime>
@@ -2003,7 +2004,7 @@
         }
     }
     // Sort it so we can apply the BySetPos. Also some logic relies on this being sorted
-    lst.sortUnique();
+    sortAndRemoveDuplicates(lst);
 
     /*if ( lst.isEmpty() ) {
       qCDebug(KCALCORE_LOG) << "         No Dates in Interval";
@@ -2029,7 +2030,7 @@
                 lst.append(tmplst[pos]);
             }
         }
-        lst.sortUnique();
+        sortAndRemoveDuplicates(lst);
     }
 
     return lst;