diff --git a/CHANGELOG.md b/CHANGELOG.md
index 49bf85d..739b043 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,9 @@ and this project adheres to
   Color to a polynomial fitted to data provided by Warren and Brandt in their
   paper Optical Constants of Ice from The Ultraviolet to The Microwave, which
   is what HaloPoint 2.0 used to use
+- HaloRay now remembers which folder you opened last when loading or saving
+  files like simulation parameter files or images, and opens the file dialog
+  picker in that same folder the next time
 
 ## 4.0.1 - 2021-08-26
 
diff --git a/src/haloray-core/gui/mainWindow.cpp b/src/haloray-core/gui/mainWindow.cpp
index 44e1790..68610bb 100644
--- a/src/haloray-core/gui/mainWindow.cpp
+++ b/src/haloray-core/gui/mainWindow.cpp
@@ -98,39 +98,43 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), m_previousTimedIt
         auto defaultFilename = QString("haloray_%1.png")
                                    .arg(currentTime)
                                    .replace(":", "-");
+        auto defaultFilePath = getLatestAccessedFolder().absoluteFilePath(defaultFilename);
         QString filename = QFileDialog::getSaveFileName(this,
                                                         tr("Save File"),
-                                                        defaultFilename,
+                                                        defaultFilePath,
                                                         tr("Images (*.png)"));
 
-        if (!filename.isNull())
-        {
-            image.save(filename, "PNG", 50);
-        }
+        if (filename.isNull()) return;
+
+        image.save(filename, "PNG", 50);
+        updateLatestAccessedFolder(filename);
     });
     connect(m_saveSimulationAction, &QAction::triggered, [this]() {
         auto currentTime = QDateTime::currentDateTimeUtc().toString(Qt::DateFormat::ISODate);
         auto defaultFilename = QString("haloray_sim_%1.ini")
                                    .arg(currentTime)
                                    .replace(":", "-");
+        auto defaultFilePath = getLatestAccessedFolder().absoluteFilePath(defaultFilename);
         QString filename = QFileDialog::getSaveFileName(this,
                                                         tr("Save File"),
-                                                        defaultFilename,
+                                                        defaultFilePath,
                                                         tr("Simulation files (*.ini)"));
 
         if (filename.isNull()) return;
 
         StateSaver::SaveState(filename, m_engine, m_crystalRepository.get());
+        updateLatestAccessedFolder(filename);
     });
     connect(m_loadSimulationAction, &QAction::triggered, [this]() {
         QString filename = QFileDialog::getOpenFileName(this,
                                                         tr("Open file"),
-                                                        QString(),
+                                                        getLatestAccessedFolder().absolutePath(),
                                                         tr("Simulation files (*.ini)"));
 
         if (filename.isNull()) return;
 
         StateSaver::LoadState(filename, m_simulationStateModel, m_crystalModel);
+        updateLatestAccessedFolder(filename);
     });
     connect(m_openCrystalPreviewWindow, &QAction::triggered, [this]() {
         auto previewWindow = new CrystalPreviewWindow(m_crystalModel, m_crystalSettingsWidget->getCurrentPopulationIndex(), this);
@@ -273,4 +277,24 @@ void HaloRay::MainWindow::restartSimulation()
     m_openGLWidget->update();
 }
 
+QDir MainWindow::getLatestAccessedFolder() const
+{
+    QSettings settings;
+    QString pathString = settings.value("filedialog/latestFolder", QString()).toString();
+    QDir dir(pathString);
+    if (dir.exists()) {
+        return dir;
+    }
+
+    return QDir();
+}
+
+void MainWindow::updateLatestAccessedFolder(QString fileOrDirPath)
+{
+    QFileInfo fileInfo(fileOrDirPath);
+    QString path = fileInfo.absoluteDir().path();
+    QSettings settings;
+    settings.setValue("filedialog/latestFolder", path);
+}
+
 }
diff --git a/src/haloray-core/gui/mainWindow.h b/src/haloray-core/gui/mainWindow.h
index 66aebc2..63c8292 100644
--- a/src/haloray-core/gui/mainWindow.h
+++ b/src/haloray-core/gui/mainWindow.h
@@ -4,11 +4,11 @@
 #include <QTimer>
 #include "gui/models/simulationStateModel.h"
 
-
 class QDoubleSpinBox;
 class QProgressBar;
 class QScrollArea;
 class QAction;
+class QDir;
 
 namespace HaloRay
 {
@@ -39,6 +39,9 @@ class MainWindow : public QMainWindow
     void setupRenderTimer();
     void restartSimulation();
 
+    QDir getLatestAccessedFolder() const;
+    void updateLatestAccessedFolder(QString fileOrDirPath);
+
     GeneralSettingsWidget *m_generalSettingsWidget;
     CrystalSettingsWidget *m_crystalSettingsWidget;
     ViewSettingsWidget *m_viewSettingsWidget;