diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -37,8 +37,8 @@
 
 remove_definitions(-DQT_NO_CAST_FROM_ASCII -DQT_NO_CAST_TO_ASCII)
 
-
 ########### Targets ###########
+add_definitions(-DQT_NO_FOREACH)
 add_subdirectory(src)
 
 if(BUILD_TESTING)
diff --git a/autotests/testholidayregion.h b/autotests/testholidayregion.h
--- a/autotests/testholidayregion.h
+++ b/autotests/testholidayregion.h
@@ -42,7 +42,7 @@
 
 private:
     void printMetadata(const KHolidays::HolidayRegion &region);
-    void printHolidays(KHolidays::Holiday::List holidays);
+    void printHolidays(const KHolidays::Holiday::List &holidays);
     void parseRegionCalendarYear(const KHolidays::HolidayRegion &region, int year,
                                  const QString &calendarType = "gregorian");
     void parseRegionDateRange(const KHolidays::HolidayRegion &region, const QDate &startDate, const QDate &endDate);
diff --git a/autotests/testholidayregion.cpp b/autotests/testholidayregion.cpp
--- a/autotests/testholidayregion.cpp
+++ b/autotests/testholidayregion.cpp
@@ -44,10 +44,10 @@
     qDebug() << "";
 }
 
-void HolidayRegionTest::printHolidays(KHolidays::Holiday::List holidays)
+void HolidayRegionTest::printHolidays(const KHolidays::Holiday::List &holidays)
 {
     if (!holidays.isEmpty()) {
-        foreach (const KHolidays::Holiday &holiday, holidays) {
+        for (const KHolidays::Holiday &holiday : holidays) {
             qDebug() << "Date = " << holiday.observedStartDate().toString(Qt::ISODate)
                      << " Duration = " << holiday.duration()
                      << " Name = " << holiday.name();
@@ -139,15 +139,15 @@
 void HolidayRegionTest::testRegions()
 {
     qDebug() << "Available region codes:";
-    QStringList regionCodes = KHolidays::HolidayRegion::regionCodes();
-    foreach (const QString &regionCode, regionCodes) {
+    const QStringList regionCodes = KHolidays::HolidayRegion::regionCodes();
+    for (const QString &regionCode : regionCodes) {
         KHolidays::HolidayRegion testRegion(regionCode);
         qDebug() << regionCode << " = " << testRegion.name();
     }
     qDebug() << "";
 
     qDebug() << "This years holidays:";
-    foreach (const QString &regionCode, regionCodes) {
+    for (const QString &regionCode : regionCodes) {
         KHolidays::HolidayRegion testRegion(regionCode);
         printMetadata(testRegion);
         parseRegionCalendarYear(testRegion, QDate::currentDate().year());
diff --git a/src/holidayregion.cpp b/src/holidayregion.cpp
--- a/src/holidayregion.cpp
+++ b/src/holidayregion.cpp
@@ -1128,7 +1128,7 @@
             languageSubdivisionAndLanguageMatch, languageSubdivisionOnlyMatch;
 
     const QStringList regionList = KHolidays::HolidayRegion::regionCodes();
-    foreach (const QString &regionCode, regionList) {
+    for (const QString &regionCode : regionList) {
         QString regionCountry = KHolidays::HolidayRegion::countryCode(regionCode).toLower();
         QString regionSubdivisionCountry;
         if (regionCountry.split(QLatin1Char('-')).count() > 1) {
diff --git a/src/parsers/plan2/holidayparserdriverplan.cpp b/src/parsers/plan2/holidayparserdriverplan.cpp
--- a/src/parsers/plan2/holidayparserdriverplan.cpp
+++ b/src/parsers/plan2/holidayparserdriverplan.cpp
@@ -95,7 +95,7 @@
 void HolidayParserDriverPlan::parse()
 {
     // Parse the file using every calendar system in the file
-    foreach (const QString &calendarType, m_fileCalendarTypes) {
+    for (const QString &calendarType : qAsConst(m_fileCalendarTypes)) {
 
         // Cater for events defined in other Calendar Systems where request year could cover 2 or 3 event years
         // Perhaps also parse year before and year after to allow events to span years or shift to other year?
@@ -337,7 +337,7 @@
 // Return the jd of an existing event, assumes unique names and correct order in file
 int HolidayParserDriverPlan::julianDayFromEventName(const QString &eventName)
 {
-    foreach (const KHolidays::Holiday &thisHoliday, m_resultList) {
+    for (const KHolidays::Holiday &thisHoliday : qAsConst(m_resultList)) {
         if (thisHoliday.name() == eventName) {
             return thisHoliday.observedStartDate().toJulianDay();
         }