diff --git a/include/mainwindow.h b/include/mainwindow.h
index 16bc3cc8..4eae446f 100644
--- a/include/mainwindow.h
+++ b/include/mainwindow.h
@@ -388,6 +388,7 @@ private:
     void redrawMetatileSelection();
 
     QObjectList shortcutableObjects() const;
+    QTableWidgetItem * createNewCustomHeaderItem(QJsonValue value);
 };
 
 enum MapListUserRoles {
diff --git a/src/editor.cpp b/src/editor.cpp
index 290a30b6..50da1ca2 100644
--- a/src/editor.cpp
+++ b/src/editor.cpp
@@ -1948,17 +1948,35 @@ void Editor::toggleBorderVisibility(bool visible, bool enableScriptCallback)
 
 void Editor::updateCustomMapHeaderValues(QTableWidget *table)
 {
-    QMap<QString, QString> fields;
+    QMap<QString, QJsonValue> fields;
     for (int row = 0; row < table->rowCount(); row++) {
-        QString keyStr = "";
-        QString valueStr = "";
-        QTableWidgetItem *key = table->item(row, 0);
-        QTableWidgetItem *value = table->item(row, 1);
-        if (key) keyStr = key->text();
-        if (value) valueStr = value->text();
-        fields[keyStr] = valueStr;
+        QString key = "";
+        QString value = "";
+        QTableWidgetItem *keyItem = table->item(row, 0);
+        QTableWidgetItem *valueItem = table->item(row, 1);
+        if (keyItem) key = keyItem->text();
+        if (!key.isEmpty() && valueItem) {
+            // Use the original table value to determine which type the input text should be saved as.
+            QJsonValue value = valueItem->data(Qt::UserRole).toJsonValue();
+            switch (value.type())
+            {
+            case QJsonValue::String:
+                value = QJsonValue(valueItem->text());
+                break;
+            case QJsonValue::Double:
+                value = QJsonValue(valueItem->text().toInt());
+                break;
+            case QJsonValue::Bool:
+                value = QJsonValue(valueItem->checkState() == Qt::Checked);
+                break;
+            default:
+                // Arrays and objects can't be updated via the table, just preserve the original value.
+                break;
+            }
+            fields[key] = value;
+        }
     }
-    //map->customHeaders = fields;
+    map->customHeaders = fields;
     emit editedMapData();
 }
 
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index cba737f0..94055e76 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -803,27 +803,10 @@ void MainWindow::displayMapProperties() {
     ui->tableWidget_CustomHeaderFields->blockSignals(true);
     ui->tableWidget_CustomHeaderFields->setRowCount(0);
     for (auto it = map->customHeaders.begin(); it != map->customHeaders.end(); it++) {
-        QTableWidgetItem * tableItem;
-        QJsonValue value = it.value();
-        switch (value.type())
-        {
-        case QJsonValue::String:
-        case QJsonValue::Double:
-            tableItem = new QTableWidgetItem(ParseUtil::jsonToQString(value));
-            break;
-        case QJsonValue::Bool:
-            tableItem = new QTableWidgetItem("");
-            tableItem->setCheckState(value.toBool() ? Qt::Checked : Qt::Unchecked);
-            break;
-        default:
-            tableItem = new QTableWidgetItem("This value cannot be edited from this table");
-            tableItem->setFlags(Qt::NoItemFlags);
-            break;
-        }
         int rowIndex = ui->tableWidget_CustomHeaderFields->rowCount();
         ui->tableWidget_CustomHeaderFields->insertRow(rowIndex);
         ui->tableWidget_CustomHeaderFields->setItem(rowIndex, 0, new QTableWidgetItem(it.key()));
-        ui->tableWidget_CustomHeaderFields->setItem(rowIndex, 1, tableItem);
+        ui->tableWidget_CustomHeaderFields->setItem(rowIndex, 1, createNewCustomHeaderItem(it.value()));
     }
     ui->tableWidget_CustomHeaderFields->horizontalHeader()->setSectionResizeMode(QHeaderView::ResizeToContents);
     ui->tableWidget_CustomHeaderFields->blockSignals(false);
@@ -3097,11 +3080,35 @@ void MainWindow::togglePreferenceSpecificUi() {
         ui->actionOpen_Project_in_Text_Editor->setEnabled(true);
 }
 
+QTableWidgetItem * MainWindow::createNewCustomHeaderItem(QJsonValue value) {
+    QTableWidgetItem * tableItem;
+    switch (value.type())
+    {
+    case QJsonValue::String:
+    case QJsonValue::Double:
+        tableItem = new QTableWidgetItem(ParseUtil::jsonToQString(value));
+        break;
+    case QJsonValue::Bool:
+        tableItem = new QTableWidgetItem("");
+        tableItem->setCheckState(value.toBool() ? Qt::Checked : Qt::Unchecked);
+        break;
+    default:
+        tableItem = new QTableWidgetItem("This value cannot be edited from this table");
+        tableItem->setFlags(Qt::NoItemFlags);
+        break;
+    }
+    tableItem->setData(Qt::UserRole, value); // Save the original value/type for when it's written back to the project
+    return tableItem;
+}
+
 void MainWindow::on_pushButton_AddCustomHeaderField_clicked()
 {
     int rowIndex = this->ui->tableWidget_CustomHeaderFields->rowCount();
     this->ui->tableWidget_CustomHeaderFields->insertRow(rowIndex);
     this->ui->tableWidget_CustomHeaderFields->selectRow(rowIndex);
+    // TODO: New items default to string, allow type selection
+    QJsonValue defaultValue = QJsonValue(QString(""));
+    this->ui->tableWidget_CustomHeaderFields->setItem(rowIndex, 1, createNewCustomHeaderItem(defaultValue));
     this->editor->updateCustomMapHeaderValues(this->ui->tableWidget_CustomHeaderFields);
 }
 
diff --git a/src/project.cpp b/src/project.cpp
index 7b41350e..6207fe5b 100644
--- a/src/project.cpp
+++ b/src/project.cpp
@@ -1440,7 +1440,28 @@ void Project::saveMap(Map *map) {
 
     // Custom header fields.
     for (QString key : map->customHeaders.keys()) {
-        //mapObj[key] = map->customHeaders[key];
+        QJsonValue value = map->customHeaders[key];
+        switch (value.type())
+        {
+        default:
+        case QJsonValue::String:
+            mapObj[key] = value.toString();
+            break;
+        case QJsonValue::Double:
+            mapObj[key] = value.toInt();
+            break;
+        case QJsonValue::Bool:
+            mapObj[key] = value.toBool();
+            break;
+        case QJsonValue::Array:
+            // TODO: Custom array values are replaced with empty strings
+            mapObj[key] = value.toString();
+            break;
+        case QJsonValue::Object:
+            // TODO: Custom object values are replaced with empty strings
+            mapObj[key] = value.toString();
+            break;
+        }
     }
 
     OrderedJson mapJson(mapObj);