diff --git a/src/qwt_date.cpp b/src/qwt_date.cpp
index a9920c9..0699325 100644
--- a/src/qwt_date.cpp
+++ b/src/qwt_date.cpp
@@ -132,7 +132,7 @@ static inline void qwtFloorTime(
     const Qt::TimeSpec timeSpec = dt.timeSpec();
 
     if ( timeSpec == Qt::LocalTime )
-        dt = dt.toTimeSpec( Qt::UTC );
+        dt = dt.toTimeZone(QTimeZone::UTC);
 
     const QTime t = dt.time();
     switch( intervalType )
@@ -157,13 +157,13 @@ static inline void qwtFloorTime(
     }
 
     if ( timeSpec == Qt::LocalTime )
-        dt = dt.toTimeSpec( Qt::LocalTime );
+        dt = dt.toTimeZone( QTimeZone::LocalTime );
 }
 
 static inline QDateTime qwtToTimeSpec(
-    const QDateTime& dt, Qt::TimeSpec spec )
+    const QDateTime& dt, QTimeZone spec )
 {
-    if ( dt.timeSpec() == spec )
+    if ( dt.timeZone() == spec )
         return dt;
 
     const qint64 jd = dt.date().toJulianDay();
@@ -175,11 +175,12 @@ static inline QDateTime qwtToTimeSpec(
         // for those dates
 
         QDateTime dt2 = dt;
-        dt2.setTimeSpec( spec );
+        dt2.setTimeZone( spec );
         return dt2;
     }
-
-    return dt.toTimeSpec( spec );
+    QDateTime dt_copy = dt;
+    dt_copy.setTimeZone( spec );
+    return dt_copy;
 }
 
 #if 0
@@ -258,7 +259,7 @@ static inline QDate qwtToDate( int year, int month = 1, int day = 1 )
    \sa toDouble(), QDateTime::setMSecsSinceEpoch()
    \note The return datetime for Qt::OffsetFromUTC will be Qt::UTC
  */
-QDateTime QwtDate::toDateTime( double value, Qt::TimeSpec timeSpec )
+QDateTime QwtDate::toDateTime( double value, QTimeZone timeSpec )
 {
     const int msecsPerDay = 86400000;
 
@@ -277,9 +278,9 @@ QDateTime QwtDate::toDateTime( double value, Qt::TimeSpec timeSpec )
 
     static const QTime timeNull( 0, 0, 0, 0 );
 
-    QDateTime dt( d, timeNull.addMSecs( msecs ), Qt::UTC );
+    QDateTime dt( d, timeNull.addMSecs( msecs ), QTimeZone::UTC );
 
-    if ( timeSpec == Qt::LocalTime )
+    if ( timeSpec == QTimeZone::LocalTime )
         dt = qwtToTimeSpec( dt, timeSpec );
 
     return dt;
@@ -299,7 +300,7 @@ double QwtDate::toDouble( const QDateTime& dateTime )
 {
     const int msecsPerDay = 86400000;
 
-    const QDateTime dt = qwtToTimeSpec( dateTime, Qt::UTC );
+    const QDateTime dt = qwtToTimeSpec( dateTime, QTimeZone::UTC );
 
     const double days = dt.date().toJulianDay() - QwtDate::JulianDayForEpoch;
 
@@ -653,7 +654,7 @@ int QwtDate::utcOffset( const QDateTime& dateTime )
         }
         default:
         {
-            const QDateTime dt1( dateTime.date(), dateTime.time(), Qt::UTC );
+            const QDateTime dt1( dateTime.date(), dateTime.time(), QTimeZone::UTC );
             seconds = dateTime.secsTo( dt1 );
         }
     }
diff --git a/src/qwt_date.h b/src/qwt_date.h
index 49a1f0d..9954ca6 100644
--- a/src/qwt_date.h
+++ b/src/qwt_date.h
@@ -12,6 +12,7 @@
 
 #include "qwt_global.h"
 #include <qdatetime.h>
+#include <qtimezone.h>
 
 /*!
    \brief A collection of methods around date/time values
@@ -109,7 +110,7 @@ class QWT_EXPORT QwtDate
     static QDate maxDate();
 
     static QDateTime toDateTime( double value,
-        Qt::TimeSpec = Qt::UTC );
+        QTimeZone = QTimeZone::UTC );
 
     static double toDouble( const QDateTime& );
 
diff --git a/src/qwt_date_scale_draw.cpp b/src/qwt_date_scale_draw.cpp
index 57af0fd..fc5eb7e 100644
--- a/src/qwt_date_scale_draw.cpp
+++ b/src/qwt_date_scale_draw.cpp
@@ -13,8 +13,8 @@
 class QwtDateScaleDraw::PrivateData
 {
   public:
-    explicit PrivateData( Qt::TimeSpec spec )
-        : timeSpec( spec )
+    explicit PrivateData( QTimeZone zone )
+        : timeZone( zone )
         , utcOffset( 0 )
         , week0Type( QwtDate::FirstThursday )
     {
@@ -28,7 +28,7 @@ class QwtDateScaleDraw::PrivateData
         dateFormats[ QwtDate::Year ] = "yyyy";
     }
 
-    Qt::TimeSpec timeSpec;
+    QTimeZone timeZone;
     int utcOffset;
     QwtDate::Week0Type week0Type;
     QString dateFormats[ QwtDate::Year + 1 ];
@@ -45,9 +45,9 @@ class QwtDateScaleDraw::PrivateData
 
    \sa setTimeSpec(), setWeek0Type()
  */
-QwtDateScaleDraw::QwtDateScaleDraw( Qt::TimeSpec timeSpec )
+QwtDateScaleDraw::QwtDateScaleDraw( QTimeZone timeZone )
 {
-    m_data = new PrivateData( timeSpec );
+    m_data = new PrivateData( timeZone );
 }
 
 //! Destructor
@@ -62,18 +62,18 @@ QwtDateScaleDraw::~QwtDateScaleDraw()
    \param timeSpec Time specification
    \sa timeSpec(), setUtcOffset(), toDateTime()
  */
-void QwtDateScaleDraw::setTimeSpec( Qt::TimeSpec timeSpec )
+void QwtDateScaleDraw::setTimeZone( QTimeZone timeZone )
 {
-    m_data->timeSpec = timeSpec;
+    m_data->timeZone = timeZone;
 }
 
 /*!
    \return Time specification used for the tick labels
    \sa setTimeSpec(), utcOffset(), toDateTime()
  */
-Qt::TimeSpec QwtDateScaleDraw::timeSpec() const
+QTimeZone QwtDateScaleDraw::timeZone() const
 {
-    return m_data->timeSpec;
+    return m_data->timeZone;
 }
 
 /*!
@@ -268,11 +268,13 @@ QwtDate::IntervalType QwtDateScaleDraw::intervalType(
  */
 QDateTime QwtDateScaleDraw::toDateTime( double value ) const
 {
-    QDateTime dt = QwtDate::toDateTime( value, m_data->timeSpec );
-    if ( m_data->timeSpec == Qt::OffsetFromUTC )
+    QDateTime dt = QwtDate::toDateTime( value, m_data->timeZone );
+    if ( m_data->timeZone == QTimeZone::LocalTime )
     {
         dt = dt.addSecs( m_data->utcOffset );
-#if QT_VERSION >= 0x050200
+#if QT_VERSION >= 0x060000
+        dt.setTimeZone( QTimeZone(m_data->utcOffset) );
+#elif QT_VERSION >= 0x050200
         dt.setOffsetFromUtc( m_data->utcOffset );
 #else
         dt.setUtcOffset( m_data->utcOffset );
diff --git a/src/qwt_date_scale_draw.h b/src/qwt_date_scale_draw.h
index c49fd1e..c8a0f22 100644
--- a/src/qwt_date_scale_draw.h
+++ b/src/qwt_date_scale_draw.h
@@ -52,14 +52,14 @@
 class QWT_EXPORT QwtDateScaleDraw : public QwtScaleDraw
 {
   public:
-    explicit QwtDateScaleDraw( Qt::TimeSpec = Qt::LocalTime );
+    explicit QwtDateScaleDraw( QTimeZone timeZone = QTimeZone::LocalTime );
     virtual ~QwtDateScaleDraw();
 
     void setDateFormat( QwtDate::IntervalType, const QString& );
     QString dateFormat( QwtDate::IntervalType ) const;
 
-    void setTimeSpec( Qt::TimeSpec );
-    Qt::TimeSpec timeSpec() const;
+    void setTimeZone( QTimeZone );
+    QTimeZone timeZone() const;
 
     void setUtcOffset( int seconds );
     int utcOffset() const;
diff --git a/src/qwt_date_scale_engine.cpp b/src/qwt_date_scale_engine.cpp
index fce6f6f..5267eea 100644
--- a/src/qwt_date_scale_engine.cpp
+++ b/src/qwt_date_scale_engine.cpp
@@ -717,15 +717,15 @@ static QwtScaleDiv qwtDivideToYears(
 class QwtDateScaleEngine::PrivateData
 {
   public:
-    explicit PrivateData( Qt::TimeSpec spec )
-        : timeSpec( spec )
+    explicit PrivateData( QTimeZone zone )
+        : timeZone( zone )
         , utcOffset( 0 )
         , week0Type( QwtDate::FirstThursday )
         , maxWeeks( 4 )
     {
     }
 
-    Qt::TimeSpec timeSpec;
+    QTimeZone timeZone;
     int utcOffset;
     QwtDate::Week0Type week0Type;
     int maxWeeks;
@@ -744,10 +744,10 @@ class QwtDateScaleEngine::PrivateData
 
    \sa setTimeSpec(), setMaxWeeks(), setWeek0Type()
  */
-QwtDateScaleEngine::QwtDateScaleEngine( Qt::TimeSpec timeSpec )
+QwtDateScaleEngine::QwtDateScaleEngine( QTimeZone timeZone )
     : QwtLinearScaleEngine( 10 )
 {
-    m_data = new PrivateData( timeSpec );
+    m_data = new PrivateData( timeZone );
 }
 
 //! Destructor
@@ -762,18 +762,18 @@ QwtDateScaleEngine::~QwtDateScaleEngine()
    \param timeSpec Time specification
    \sa timeSpec(), setUtcOffset(), toDateTime()
  */
-void QwtDateScaleEngine::setTimeSpec( Qt::TimeSpec timeSpec )
+void QwtDateScaleEngine::setTimeZone( QTimeZone timeZone )
 {
-    m_data->timeSpec = timeSpec;
+    m_data->timeZone = timeZone;
 }
 
 /*!
    \return Time specification used by the engine
    \sa setTimeSpec(), utcOffset(), toDateTime()
  */
-Qt::TimeSpec QwtDateScaleEngine::timeSpec() const
+QTimeZone QwtDateScaleEngine::timeZone() const
 {
-    return m_data->timeSpec;
+    return m_data->timeZone;
 }
 
 /*!
@@ -1116,7 +1116,7 @@ QDateTime QwtDateScaleEngine::alignDate(
     if ( dateTime.timeSpec() == Qt::OffsetFromUTC )
     {
 #if QT_VERSION >= 0x050200
-        dt.setOffsetFromUtc( 0 );
+        dt.setTimeZone( QTimeZone::UTC );
 #else
         dt.setUtcOffset( 0 );
 #endif
@@ -1277,7 +1277,9 @@ QDateTime QwtDateScaleEngine::alignDate(
 
     if ( dateTime.timeSpec() == Qt::OffsetFromUTC )
     {
-#if QT_VERSION >= 0x050200
+#if QT_VERSION >= 0x060000
+    dt.setTimeZone( QTimeZone(dateTime.offsetFromUtc()) );
+#elif QT_VERSION >= 0x050200
         dt.setOffsetFromUtc( dateTime.offsetFromUtc() );
 #else
         dt.setUtcOffset( dateTime.utcOffset() );
@@ -1297,19 +1299,22 @@ QDateTime QwtDateScaleEngine::alignDate(
  */
 QDateTime QwtDateScaleEngine::toDateTime( double value ) const
 {
-    QDateTime dt = QwtDate::toDateTime( value, m_data->timeSpec );
+    QDateTime dt = QwtDate::toDateTime( value, m_data->timeZone );
     if ( !dt.isValid() )
     {
         const QDate date = ( value <= 0.0 )
             ? QwtDate::minDate() : QwtDate::maxDate();
 
-        dt = QDateTime( date, QTime( 0, 0 ), m_data->timeSpec );
+        dt = QDateTime( date, QTime( 0, 0 ), m_data->timeZone );
     }
 
-    if ( m_data->timeSpec == Qt::OffsetFromUTC )
+    if ( m_data->timeZone == QTimeZone::LocalTime )
     {
         dt = dt.addSecs( m_data->utcOffset );
-#if QT_VERSION >= 0x050200
+
+#if QT_VERSION >= 0x060000
+        dt.setTimeZone( QTimeZone(m_data->utcOffset) );
+#elif QT_VERSION >= 0x050200
         dt.setOffsetFromUtc( m_data->utcOffset );
 #else
         dt.setUtcOffset( m_data->utcOffset );
diff --git a/src/qwt_date_scale_engine.h b/src/qwt_date_scale_engine.h
index 6e5f68b..366a074 100644
--- a/src/qwt_date_scale_engine.h
+++ b/src/qwt_date_scale_engine.h
@@ -42,11 +42,11 @@
 class QWT_EXPORT QwtDateScaleEngine : public QwtLinearScaleEngine
 {
   public:
-    explicit QwtDateScaleEngine( Qt::TimeSpec = Qt::LocalTime );
+    explicit QwtDateScaleEngine( QTimeZone = QTimeZone::LocalTime );
     virtual ~QwtDateScaleEngine();
 
-    void setTimeSpec( Qt::TimeSpec );
-    Qt::TimeSpec timeSpec() const;
+    void setTimeZone( QTimeZone );
+    QTimeZone timeZone() const;
 
     void setUtcOffset( int seconds );
     int utcOffset() const;