diff --git a/src/Platform.h b/src/Platform.h
index a379d853..144fce19 100644
--- a/src/Platform.h
+++ b/src/Platform.h
@@ -337,6 +337,9 @@ void WriteGBASave(const u8* savedata, u32 savelen, u32 writeoffset, u32 writelen
 /// @param writelen The number of bytes that were written to firmware.
 void WriteFirmware(const SPI_Firmware::Firmware& firmware, u32 writeoffset, u32 writelen);
 
+// called when the RTC date/time is changed and the frontend might need to take it into account
+void WriteDateTime(int year, int month, int day, int hour, int minute, int second);
+
 
 // local multiplayer comm interface
 // packet type: DS-style TX header (12 bytes) + original 802.11 frame
diff --git a/src/RTC.cpp b/src/RTC.cpp
index 8d3fb401..3272275d 100644
--- a/src/RTC.cpp
+++ b/src/RTC.cpp
@@ -455,6 +455,13 @@ void WriteDateTime(int num, u8 val)
     }
 }
 
+void SaveDateTime()
+{
+    int y, m, d, h, i, s;
+    GetDateTime(y, m, d, h, i, s);
+    Platform::WriteDateTime(y, m, d, h, i, s);
+}
+
 void CmdRead()
 {
     if ((CurCmd & 0x0F) == 0x06)
@@ -607,11 +614,15 @@ void CmdWrite(u8 val)
         case 0x20:
             if (InputPos <= 7)
                 WriteDateTime(InputPos, val);
+            if (InputPos == 7)
+                SaveDateTime();
             break;
 
         case 0x60:
             if (InputPos <= 3)
                 WriteDateTime(InputPos+4, val);
+            if (InputPos == 3)
+                SaveDateTime();
             break;
 
         case 0x10:
diff --git a/src/frontend/qt_sdl/Config.cpp b/src/frontend/qt_sdl/Config.cpp
index ba91068d..cfd4b1c0 100644
--- a/src/frontend/qt_sdl/Config.cpp
+++ b/src/frontend/qt_sdl/Config.cpp
@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
+#include <inttypes.h>
 #include "Platform.h"
 #include "Config.h"
 
@@ -140,10 +141,7 @@ int MouseHideSeconds;
 
 bool PauseLostFocus;
 
-int RTCMode;
-std::string RTCLastTime;
-std::string RTCLastHostTime;
-std::string RTCNewTime;
+int64_t RTCOffset;
 
 bool DSBatteryLevelOkay;
 int DSiBatteryLevel;
@@ -344,10 +342,7 @@ ConfigEntry ConfigFile[] =
     {"MouseHideSeconds", 0, &MouseHideSeconds, 5, false},
     {"PauseLostFocus",   1, &PauseLostFocus,   false, false},
 
-    {"RTCMode",         0, &RTCMode,         0, true},
-    {"RTCLastTime",     2, &RTCLastTime,     (std::string)"", true},
-    {"RTCLastHostTime", 2, &RTCLastHostTime, (std::string)"", true},
-    {"RTCNewTime",      2, &RTCNewTime,      (std::string)"", true},
+    {"RTCOffset",       3, &RTCOffset,       0LL, true},
 
     {"DSBatteryLevelOkay",   1, &DSBatteryLevelOkay, true, true},
     {"DSiBatteryLevel",    0, &DSiBatteryLevel, 0xF, true},
@@ -416,6 +411,7 @@ void LoadFile(int inst)
                 case 0: *(int*)entry->Value = strtol(entryval, NULL, 10); break;
                 case 1: *(bool*)entry->Value = strtol(entryval, NULL, 10) ? true:false; break;
                 case 2: *(std::string*)entry->Value = entryval; break;
+                case 3: *(int64_t*)entry->Value = strtoll(entryval, NULL, 10); break;
                 }
 
                 break;
@@ -436,6 +432,7 @@ void Load()
         case 0: *(int*)entry->Value = std::get<int>(entry->Default); break;
         case 1: *(bool*)entry->Value = std::get<bool>(entry->Default); break;
         case 2: *(std::string*)entry->Value = std::get<std::string>(entry->Default); break;
+        case 3: *(int64_t*)entry->Value = std::get<int64_t>(entry->Default); break;
         }
     }
 
@@ -472,6 +469,7 @@ void Save()
         case 0: Platform::FileWriteFormatted(f, "%s=%d\r\n", entry->Name, *(int*)entry->Value); break;
         case 1: Platform::FileWriteFormatted(f, "%s=%d\r\n", entry->Name, *(bool*)entry->Value ? 1:0); break;
         case 2: Platform::FileWriteFormatted(f, "%s=%s\r\n", entry->Name, (*(std::string*)entry->Value).c_str()); break;
+        case 3: Platform::FileWriteFormatted(f, "%s=%"PRId64"\r\n", entry->Name, *(int64_t*)entry->Value); break;
         }
     }
 
diff --git a/src/frontend/qt_sdl/Config.h b/src/frontend/qt_sdl/Config.h
index daa69c8b..fba9bfb0 100644
--- a/src/frontend/qt_sdl/Config.h
+++ b/src/frontend/qt_sdl/Config.h
@@ -57,9 +57,9 @@ namespace Config
 struct ConfigEntry
 {
     char Name[32];
-    int Type;           // 0=int 1=bool 2=string
+    int Type;           // 0=int 1=bool 2=string 3=64bit int
     void* Value;        // pointer to the value variable
-    std::variant<int, bool, std::string> Default;
+    std::variant<int, bool, std::string, int64_t> Default;
     bool InstanceUnique; // whether the setting can exist individually for each instance in multiplayer
 };
 
@@ -185,10 +185,7 @@ extern bool MouseHide;
 extern int MouseHideSeconds;
 extern bool PauseLostFocus;
 
-extern int RTCMode;
-extern std::string RTCLastTime;
-extern std::string RTCLastHostTime;
-extern std::string RTCNewTime;
+extern int64_t RTCOffset;
 
 extern bool DSBatteryLevelOkay;
 extern int DSiBatteryLevel;
diff --git a/src/frontend/qt_sdl/DateTimeDialog.cpp b/src/frontend/qt_sdl/DateTimeDialog.cpp
index 49ef5545..2ef96881 100644
--- a/src/frontend/qt_sdl/DateTimeDialog.cpp
+++ b/src/frontend/qt_sdl/DateTimeDialog.cpp
@@ -32,46 +32,16 @@ DateTimeDialog::DateTimeDialog(QWidget* parent) : QDialog(parent), ui(new Ui::Da
     ui->setupUi(this);
     setAttribute(Qt::WA_DeleteOnClose);
 
-    grpTimeMode = new QButtonGroup(this);
-    grpTimeMode->addButton(ui->rbSystemTime, 0);
-    grpTimeMode->addButton(ui->rbCustomTime, 1);
-    connect(grpTimeMode, SIGNAL(buttonClicked(int)), this, SLOT(onChangeTimeMode(int)));
-    grpTimeMode->button(Config::RTCMode)->setChecked(true);
-
     QDateTime now = QDateTime::currentDateTime();
-    customTime = now;
+    customTime = now.addSecs(Config::RTCOffset);
 
     ui->chkChangeTime->setChecked(false);
-
-    if (Config::RTCNewTime != "")
-    {
-        QDateTime newtime = QDateTime::fromString(QString::fromStdString(Config::RTCNewTime), Qt::ISODate);
-
-        if (newtime.isValid())
-        {
-            ui->chkChangeTime->setChecked(true);
-            ui->txtNewCustomTime->setDateTime(newtime);
-        }
-    }
-
-    if (Config::RTCLastTime != "" && Config::RTCLastHostTime != "")
-    {
-        QDateTime lasttime = QDateTime::fromString(QString::fromStdString(Config::RTCLastTime), Qt::ISODate);
-        QDateTime lasthost = QDateTime::fromString(QString::fromStdString(Config::RTCLastHostTime), Qt::ISODate);
-
-        if (lasttime.isValid() && lasthost.isValid())
-        {
-            qint64 offset = lasthost.secsTo(now);
-            customTime = lasttime.addSecs(offset);
-        }
-    }
+    ui->chkResetTime->setChecked(false);
 
     ui->lblCustomTime->setText(customTime.toString(ui->txtNewCustomTime->displayFormat()));
     startTimer(1000);
 
-    bool iscustom = (Config::RTCMode == 1);
-    ui->chkChangeTime->setEnabled(iscustom);
-    ui->txtNewCustomTime->setEnabled(iscustom && ui->chkChangeTime->isChecked());
+    ui->txtNewCustomTime->setEnabled(ui->chkChangeTime->isChecked());
 }
 
 DateTimeDialog::~DateTimeDialog()
@@ -89,12 +59,13 @@ void DateTimeDialog::done(int r)
 {
     if (r == QDialog::Accepted)
     {
-        Config::RTCMode = grpTimeMode->checkedId();
-
         if (ui->chkChangeTime->isChecked())
-            Config::RTCNewTime = ui->txtNewCustomTime->dateTime().toString(Qt::ISODate).toStdString();
-        else
-            Config::RTCNewTime = "";
+        {
+            QDateTime now = QDateTime::currentDateTime();
+            Config::RTCOffset = now.secsTo(ui->txtNewCustomTime->dateTime());
+        }
+        else if (ui->chkResetTime->isChecked())
+            Config::RTCOffset = 0;
 
         Config::Save();
     }
@@ -106,21 +77,15 @@ void DateTimeDialog::done(int r)
 
 void DateTimeDialog::on_chkChangeTime_clicked(bool checked)
 {
-    bool iscustom = (grpTimeMode->checkedId() == 1);
-
-    ui->txtNewCustomTime->setEnabled(iscustom && checked);
+    if (checked) ui->chkResetTime->setChecked(false);
+    ui->txtNewCustomTime->setEnabled(checked);
 }
 
-void DateTimeDialog::onChangeTimeMode(int mode)
+void DateTimeDialog::on_chkResetTime_clicked(bool checked)
 {
-    bool iscustom = (mode == 1);
-
-    ui->chkChangeTime->setEnabled(iscustom);
-    ui->txtNewCustomTime->setEnabled(iscustom && ui->chkChangeTime->isChecked());
+    if (checked)
+    {
+        ui->chkChangeTime->setChecked(false);
+        ui->txtNewCustomTime->setEnabled(false);
+    }
 }
-
-void setCustomTimeLabel()
-{
-    //
-}
-
diff --git a/src/frontend/qt_sdl/DateTimeDialog.h b/src/frontend/qt_sdl/DateTimeDialog.h
index 3e48f380..f13dbd09 100644
--- a/src/frontend/qt_sdl/DateTimeDialog.h
+++ b/src/frontend/qt_sdl/DateTimeDialog.h
@@ -59,13 +59,11 @@ private slots:
     void done(int r);
 
     void on_chkChangeTime_clicked(bool checked);
-    void onChangeTimeMode(int mode);
+    void on_chkResetTime_clicked(bool checked);
 
 private:
     Ui::DateTimeDialog* ui;
 
-    QButtonGroup* grpTimeMode;
-
     QDateTime customTime;
 };
 
diff --git a/src/frontend/qt_sdl/DateTimeDialog.ui b/src/frontend/qt_sdl/DateTimeDialog.ui
index f4b6eb8b..59eb677e 100644
--- a/src/frontend/qt_sdl/DateTimeDialog.ui
+++ b/src/frontend/qt_sdl/DateTimeDialog.ui
@@ -7,40 +7,17 @@
     <x>0</x>
     <y>0</y>
     <width>357</width>
-    <height>259</height>
+    <height>161</height>
    </rect>
   </property>
   <property name="windowTitle">
    <string>Date and time - melonDS</string>
   </property>
   <layout class="QVBoxLayout" name="verticalLayout">
-   <item>
-    <widget class="QGroupBox" name="groupBox">
-     <property name="title">
-      <string>General settings</string>
-     </property>
-     <layout class="QFormLayout" name="formLayout">
-      <item row="1" column="0" colspan="2">
-       <widget class="QRadioButton" name="rbCustomTime">
-        <property name="text">
-         <string>Use custom date and time</string>
-        </property>
-       </widget>
-      </item>
-      <item row="0" column="0" colspan="2">
-       <widget class="QRadioButton" name="rbSystemTime">
-        <property name="text">
-         <string>Always use system date and time</string>
-        </property>
-       </widget>
-      </item>
-     </layout>
-    </widget>
-   </item>
    <item>
     <widget class="QGroupBox" name="groupBox_2">
      <property name="title">
-      <string>Custom date and time</string>
+      <string>Date and time</string>
      </property>
      <layout class="QFormLayout" name="formLayout_2">
       <item row="0" column="0">
@@ -64,28 +41,14 @@
         </property>
        </widget>
       </item>
-      <item row="2" column="0" colspan="2">
+      <item row="2" column="0">
        <widget class="QCheckBox" name="chkChangeTime">
         <property name="text">
-         <string>Change</string>
+         <string>Change to:</string>
         </property>
        </widget>
       </item>
-      <item row="3" column="0">
-       <widget class="QLabel" name="label_3">
-        <property name="text">
-         <string>New value:</string>
-        </property>
-       </widget>
-      </item>
-      <item row="4" column="0" colspan="2">
-       <widget class="QLabel" name="label_5">
-        <property name="text">
-         <string>The new value will be applied on the next boot.</string>
-        </property>
-       </widget>
-      </item>
-      <item row="3" column="1">
+      <item row="2" column="1">
        <widget class="QDateTimeEdit" name="txtNewCustomTime">
         <property name="dateTime">
          <datetime>
@@ -125,6 +88,13 @@
         </property>
        </widget>
       </item>
+      <item row="3" column="0" colspan="2">
+       <widget class="QCheckBox" name="chkResetTime">
+        <property name="text">
+         <string>Reset to system date and time</string>
+        </property>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>
diff --git a/src/frontend/qt_sdl/Platform.cpp b/src/frontend/qt_sdl/Platform.cpp
index 0cb95740..252594c7 100644
--- a/src/frontend/qt_sdl/Platform.cpp
+++ b/src/frontend/qt_sdl/Platform.cpp
@@ -23,6 +23,7 @@
 #include <string>
 #include <QStandardPaths>
 #include <QString>
+#include <QDateTime>
 #include <QDir>
 #include <QThread>
 #include <QSemaphore>
@@ -610,6 +611,15 @@ void WriteFirmware(const SPI_Firmware::Firmware& firmware, u32 writeoffset, u32
 
 }
 
+void WriteDateTime(int year, int month, int day, int hour, int minute, int second)
+{
+    QDateTime hosttime = QDateTime::currentDateTime();
+    QDateTime time = QDateTime(QDate(year, month, day), QTime(hour, minute, second));
+
+    Config::RTCOffset = hosttime.secsTo(time);
+    Config::Save();
+}
+
 bool MP_Init()
 {
     return LocalMP::Init();
diff --git a/src/frontend/qt_sdl/ROMManager.cpp b/src/frontend/qt_sdl/ROMManager.cpp
index e7c55504..648ab676 100644
--- a/src/frontend/qt_sdl/ROMManager.cpp
+++ b/src/frontend/qt_sdl/ROMManager.cpp
@@ -595,49 +595,10 @@ void SetBatteryLevels()
 void SetDateTime()
 {
     QDateTime hosttime = QDateTime::currentDateTime();
-    QDateTime time;
-
-    if (Config::RTCMode == 0)
-    {
-        // use current system time
-
-        time = hosttime;
-    }
-    else
-    {
-        // use custom time
-
-        if (Config::RTCNewTime != "")
-        {
-            // assign a new custom time
-
-            time = QDateTime::fromString(QString::fromStdString(Config::RTCNewTime), Qt::ISODate);
-            if (!time.isValid())
-                return;
-        }
-        else if (Config::RTCLastTime != "" && Config::RTCLastHostTime != "")
-        {
-            // deduce the custom time based on the last saved times
-
-            QDateTime lasttime = QDateTime::fromString(QString::fromStdString(Config::RTCLastTime), Qt::ISODate);
-            QDateTime lasthost = QDateTime::fromString(QString::fromStdString(Config::RTCLastHostTime), Qt::ISODate);
-
-            if (lasttime.isValid() && lasthost.isValid())
-            {
-                qint64 offset = lasthost.secsTo(hosttime);
-                time = lasttime.addSecs(offset);
-            }
-            else
-                return;
-        }
-    }
+    QDateTime time = hosttime.addSecs(Config::RTCOffset);
 
     RTC::SetDateTime(time.date().year(), time.date().month(), time.date().day(),
                      time.time().hour(), time.time().minute(), time.time().second());
-
-    Config::RTCLastTime = time.toString(Qt::ISODate).toStdString();
-    Config::RTCLastHostTime = hosttime.toString(Qt::ISODate).toStdString();
-    Config::RTCNewTime = "";
 }
 
 void Reset()
diff --git a/src/frontend/qt_sdl/main.cpp b/src/frontend/qt_sdl/main.cpp
index 7088f303..f6704779 100644
--- a/src/frontend/qt_sdl/main.cpp
+++ b/src/frontend/qt_sdl/main.cpp
@@ -316,7 +316,6 @@ void EmuThread::run()
 {
     u32 mainScreenPos[3];
     Platform::FileHandle* file;
-    bool hasrun = false;
 
     NDS::Init();
 
@@ -441,8 +440,6 @@ void EmuThread::run()
 
         if (EmuRunning == emuStatus_Running || EmuRunning == emuStatus_FrameStep)
         {
-            hasrun = true;
-
             EmuStatus = emuStatus_Running;
             if (EmuRunning == emuStatus_FrameStep) EmuRunning = emuStatus_Paused;
 
@@ -673,17 +670,6 @@ void EmuThread::run()
         Platform::FileWrite(&state, sizeof(state), 1, file);
         Platform::CloseFile(file);
     }
-    if (hasrun)
-    {
-        int y, m, d, h, i, s;
-        RTC::GetDateTime(y, m, d, h, i, s);
-
-        QDateTime hosttime = QDateTime::currentDateTime();
-        QDateTime time = QDateTime(QDate(y, m, d), QTime(h, i, s));
-
-        Config::RTCLastTime = time.toString(Qt::ISODate).toStdString();
-        Config::RTCLastHostTime = hosttime.toString(Qt::ISODate).toStdString();
-    }
 
     EmuStatus = emuStatus_Exit;
 
@@ -3339,7 +3325,6 @@ int main(int argc, char** argv)
     SANITIZE(Config::ScreenSizing, 0, (int)Frontend::screenSizing_MAX);
     SANITIZE(Config::ScreenAspectTop, 0, AspectRatiosNum);
     SANITIZE(Config::ScreenAspectBot, 0, AspectRatiosNum);
-    SANITIZE(Config::RTCMode, 0, 1);
 #undef SANITIZE
 
     AudioInOut::Init();