diff --git a/ApplicationLibCode/Application/Tools/RiaQDateTimeTools.cpp b/ApplicationLibCode/Application/Tools/RiaQDateTimeTools.cpp
index 3628d4a7f6..bf398267de 100644
--- a/ApplicationLibCode/Application/Tools/RiaQDateTimeTools.cpp
+++ b/ApplicationLibCode/Application/Tools/RiaQDateTimeTools.cpp
@@ -135,7 +135,7 @@ QDateTime RiaQDateTimeTools::fromYears( double years )
 QDateTime RiaQDateTimeTools::fromTime_t( time_t t )
 {
     auto qdt = createUtcDateTime();
-    qdt.setTime_t( t );
+    qdt.setSecsSinceEpoch( t );
     return qdt;
 }
 
diff --git a/ApplicationLibCode/Commands/RicSummaryCaseRestartDialog.cpp b/ApplicationLibCode/Commands/RicSummaryCaseRestartDialog.cpp
index e48e44844f..fd4c9a8603 100644
--- a/ApplicationLibCode/Commands/RicSummaryCaseRestartDialog.cpp
+++ b/ApplicationLibCode/Commands/RicSummaryCaseRestartDialog.cpp
@@ -498,9 +498,9 @@ void RicSummaryCaseRestartDialog::appendFileInfoToGridLayout( QGridLayout*
 {
     CVF_ASSERT( gridLayout );
 
-    QDateTime startDate       = QDateTime::fromTime_t( fileInfo.startDate );
+    QDateTime startDate       = QDateTime::fromSecsSinceEpoch( fileInfo.startDate );
     QString   startDateString = startDate.toString( RiaQDateTimeTools::dateFormatString() );
-    QDateTime endDate         = QDateTime::fromTime_t( fileInfo.endDate );
+    QDateTime endDate         = QDateTime::fromSecsSinceEpoch( fileInfo.endDate );
     QString   endDateString   = endDate.toString( RiaQDateTimeTools::dateFormatString() );
     int       rowCount        = gridLayout->rowCount();
 
diff --git a/ApplicationLibCode/FileInterface/RifReaderEclipseOutput.cpp b/ApplicationLibCode/FileInterface/RifReaderEclipseOutput.cpp
index b62a94e1da..38f65a928f 100644
--- a/ApplicationLibCode/FileInterface/RifReaderEclipseOutput.cpp
+++ b/ApplicationLibCode/FileInterface/RifReaderEclipseOutput.cpp
@@ -1678,7 +1678,7 @@ void RifReaderEclipseOutput::readWellCells( const ecl_grid_type* mainEclGrid, bo
 
                 // Also see RifEclipseOutputFileAccess::timeStepsText for accessing time_t structures
                 time_t stepTime          = well_state_get_sim_time( ert_well_state );
-                wellResFrame.m_timestamp = QDateTime::fromTime_t( stepTime );
+                wellResFrame.m_timestamp = QDateTime::fromSecsSinceEpoch( stepTime );
             }
 
             // Production type
diff --git a/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryCurve.cpp b/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryCurve.cpp
index 0ef42406ba..d0afd0713f 100644
--- a/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryCurve.cpp
+++ b/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryCurve.cpp
@@ -1174,8 +1174,8 @@ void RimSummaryCurve::fieldChangedByUi( const caf::PdmFieldHandle* changedField,
                 QString description;
 
                 {
-                    QDateTime first = QDateTime::fromTime_t( curveTimeStepsX.front() );
-                    QDateTime last  = QDateTime::fromTime_t( curveTimeStepsX.back() );
+                    QDateTime first = QDateTime::fromSecsSinceEpoch( curveTimeStepsX.front() );
+                    QDateTime last  = QDateTime::fromSecsSinceEpoch( curveTimeStepsX.back() );
 
                     std::vector<QDateTime> timeSteps;
                     timeSteps.push_back( first );
@@ -1189,8 +1189,8 @@ void RimSummaryCurve::fieldChangedByUi( const caf::PdmFieldHandle* changedField,
                 }
 
                 {
-                    QDateTime first = QDateTime::fromTime_t( curveTimeStepsY.front() );
-                    QDateTime last  = QDateTime::fromTime_t( curveTimeStepsY.back() );
+                    QDateTime first = QDateTime::fromSecsSinceEpoch( curveTimeStepsY.front() );
+                    QDateTime last  = QDateTime::fromSecsSinceEpoch( curveTimeStepsY.back() );
 
                     std::vector<QDateTime> timeSteps;
                     timeSteps.push_back( first );
diff --git a/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryPlot.cpp b/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryPlot.cpp
index 0389db33e4..87a844dd91 100644
--- a/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryPlot.cpp
+++ b/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryPlot.cpp
@@ -2494,7 +2494,7 @@ void appendToExportDataForCase( QString& out, const std::vector<time_t>& timeSte
             }
         }
         out += "\n";
-        out += QDateTime::fromTime_t( timeSteps[j] ).toUTC().toString( "yyyy-MM-dd hh:mm:ss " );
+        out += QDateTime::fromSecsSinceEpoch( timeSteps[j] ).toUTC().toString( "yyyy-MM-dd hh:mm:ss " );
 
         for ( size_t k = 0; k < curveData.size(); k++ ) // curves
         {
@@ -2549,7 +2549,7 @@ void appendToExportData( QString& out, const std::vector<CurvesData>& curvesData
 
         for ( auto timeStep : allTimeSteps )
         {
-            QDateTime timseStepUtc = QDateTime::fromTime_t( timeStep ).toUTC();
+            QDateTime timseStepUtc = QDateTime::fromSecsSinceEpoch( timeStep ).toUTC();
             QString   timeText;
 
             if ( showTimeAsLongString )
diff --git a/ApplicationLibCode/UnitTests/ObservedDataParser-Test.cpp b/ApplicationLibCode/UnitTests/ObservedDataParser-Test.cpp
index 2af3674f1a..4da0bff5f7 100644
--- a/ApplicationLibCode/UnitTests/ObservedDataParser-Test.cpp
+++ b/ApplicationLibCode/UnitTests/ObservedDataParser-Test.cpp
@@ -931,7 +931,7 @@ TEST( RifKeywordBasedRsmspecParserTest, TestTimeSteps )
 
     QDateTime firstDate = RiaQDateTimeTools::fromYears( 2014.32 );
 
-    EXPECT_TRUE( firstDate == QDateTime::fromTime_t( timeSteps[0] ) );
+    EXPECT_TRUE( firstDate == QDateTime::fromSecsSinceEpoch( timeSteps[0] ) );
 }
 
 //--------------------------------------------------------------------------------------------------