diff -r f69d53c053df -r a23024fc98e0 src/mainwindow.cpp
--- a/src/mainwindow.cpp	Wed Mar 09 14:22:22 2022 +0200
+++ b/src/mainwindow.cpp	Sun Mar 13 14:51:39 2022 +0200
@@ -224,6 +224,11 @@
 	return qobject_cast<Document*>(this->ui->tabs->currentWidget());
 }
 
+const Document* MainWindow::currentDocument() const
+{
+	return qobject_cast<const Document*>(this->ui->tabs->currentWidget());
+}
+
 void MainWindow::handleDocumentSplitterChange()
 {
 	Document* currentDocument = this->currentDocument();
@@ -285,24 +290,27 @@
 {
 	if (this->currentDocument() != nullptr)
 	{
-		const ModelId modelId = {0};
-		const QString* path = this->documents.modelPath(modelId);
-		if (path == nullptr or path->isEmpty())
+		const std::optional<ModelId> modelId = this->findCurrentModelId();
+		if (modelId.has_value())
 		{
-			this->actionSaveAs();
-		}
-		else
-		{
-			QString error;
-			QTextStream errorStream{&error};
-			const bool succeeded = this->documents.saveModel(modelId, errorStream);
-			if (not succeeded)
+			const QString* path = this->documents.modelPath(*modelId);
+			if (path == nullptr or path->isEmpty())
 			{
-				QMessageBox::critical(this, tr("Save error"), error);
+				this->actionSaveAs();
 			}
 			else
 			{
-				this->addRecentlyOpenedFile(*path);
+				QString error;
+				QTextStream errorStream{&error};
+				const bool succeeded = this->documents.saveModel(*modelId, errorStream);
+				if (not succeeded)
+				{
+					QMessageBox::critical(this, tr("Save error"), error);
+				}
+				else
+				{
+					this->addRecentlyOpenedFile(*path);
+				}
 			}
 		}
 	}
@@ -315,22 +323,25 @@
 {
 	if (this->currentDocument() != nullptr)
 	{
-		const ModelId modelId = {0};
-		const QString* pathPtr = this->documents.modelPath(modelId);
-		QString defaultPath = (pathPtr != nullptr) ? *pathPtr : "";
-		const QString newPath = QFileDialog::getSaveFileName(
-			this,
-			tr("Save as…"),
-			QFileInfo{defaultPath}.absoluteDir().path(), 
-			tr("LDraw files (*.ldr *dat);;All files (*)")
-		);
-		if (not newPath.isEmpty())
+		const std::optional<ModelId> modelId = this->findCurrentModelId();
+		if (modelId.has_value())
 		{
-			QString error;
-			QTextStream errorStream{&error};
-			this->documents.setModelPath(modelId, newPath, this->libraries, errorStream);
-			this->ui->tabs->setTabText(this->ui->tabs->currentIndex(), QFileInfo{newPath}.fileName());
-			this->actionSave();
+			const QString* pathPtr = this->documents.modelPath(*modelId);
+			QString defaultPath = (pathPtr != nullptr) ? *pathPtr : "";
+			const QString newPath = QFileDialog::getSaveFileName(
+				this,
+				tr("Save as…"),
+				QFileInfo{defaultPath}.absoluteDir().path(), 
+				tr("LDraw files (*.ldr *dat);;All files (*)")
+			);
+			if (not newPath.isEmpty())
+			{
+				QString error;
+				QTextStream errorStream{&error};
+				this->documents.setModelPath(*modelId, newPath, this->libraries, errorStream);
+				this->ui->tabs->setTabText(this->ui->tabs->currentIndex(), QFileInfo{newPath}.fileName());
+				this->actionSave();
+			}
 		}
 	}
 }
@@ -397,6 +408,19 @@
 	}
 }
 
+std::optional<ModelId> MainWindow::findCurrentModelId() const
+{
+	const Document* document = this->currentDocument();
+	if (document != nullptr)
+	{
+		return this->documents.findIdForModel(&document->getModel());
+	}
+	else
+	{
+		return {};
+	}
+}
+
 void MainWindow::changeEvent(QEvent* event)
 {
 	if (event != nullptr)