diff --git a/sources/elementspanel.cpp b/sources/elementspanel.cpp
index 1eac9c8ff..349f1e9b6 100644
--- a/sources/elementspanel.cpp
+++ b/sources/elementspanel.cpp
@@ -156,9 +156,11 @@ QTreeWidgetItem *ElementsPanel::addProject(QETProject *project,
 
 	if (first_add){
 		qtwi_project -> setExpanded(true);
-		// on adding an project select first diagram
-		setCurrentItem(qtwi_project -> child(0));
-		qtwi_project -> child(0)->setSelected(true);
+		// on adding a project select first diagram, once the project item is attached
+		if (qtwi_project -> treeWidget()) {
+			setCurrentItem(qtwi_project -> child(0));
+			qtwi_project -> child(0)->setSelected(true);
+		}
 	}
 	else {
 		// 2. Check whether we can restore the previous selection
diff --git a/tests/qttest/CMakeLists.txt b/tests/qttest/CMakeLists.txt
index eb6cf36cf..25dedbbbe 100644
--- a/tests/qttest/CMakeLists.txt
+++ b/tests/qttest/CMakeLists.txt
@@ -293,6 +293,11 @@ qet_add_app_test(tst_folioimageload tst_folioimageload.cpp)
 # selection has nothing to edit for a moment (#1439).
 qet_add_app_test(tst_selectionpanelheight tst_selectionpanelheight.cpp)
 
+# Opening a project before the elements panel's first reload() left its tree
+# item detached, and selecting the item's first child crashed in QTreeModel
+# (pre-existing since a82f6de23).
+qet_add_app_test(tst_elementspanelprojectopen tst_elementspanelprojectopen.cpp)
+
 # SVG export with smaller pictures (--svg-small-pictures, the export dialog's
 # option): a picture drawn at a tenth of its size is stored at four times
 # that, a small one whole; without the option every picture is whole.
diff --git a/tests/qttest/tst_elementspanelprojectopen.cpp b/tests/qttest/tst_elementspanelprojectopen.cpp
new file mode 100644
index 000000000..41cb1b8cf
--- /dev/null
+++ b/tests/qttest/tst_elementspanelprojectopen.cpp
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include "qetapptest.h"
+
+#include "elementspanel.h"
+#include "projectview.h"
+#include "qetproject.h"
+
+// projectWasOpened() adds the project to the elements panel. Before the panel's
+// first reload() the project's tree item is left detached (treeWidget() ==
+// nullptr), and selecting its first child crashed in QTreeModel
+// (pre-existing since a82f6de23).
+class tst_elementspanelprojectopen : public QObject
+{
+	Q_OBJECT
+
+	private slots:
+		void addProjectBeforeReloadDoesNotCrash()
+		{
+				// A real one-folio project from the running app; diagrams()
+				// builds the lazy folio, so the project item will have a child.
+			QETDiagramEditor *editor = QetAppTest::editor();
+			QVERIFY(editor);
+			QVERIFY(editor->newProject());
+			ProjectView *pv = editor->currentProjectView();
+			QVERIFY(pv);
+			QETProject *project = pv->project();
+			QVERIFY(project);
+			QVERIFY(!project->diagrams().isEmpty());
+
+				// Fresh panel: reload() has not run, so the project item is inserted detached.
+			ElementsPanel panel;
+
+				// Without the guard this selects a detached item; with it, nothing is selected.
+			panel.projectWasOpened(project);
+
+			QTreeWidgetItem *current = panel.currentItem();
+			QVERIFY2(current == nullptr || current->treeWidget() == &panel,
+				"the panel selected a detached item it does not own");
+		}
+};
+
+QET_APP_TEST_MAIN(tst_elementspanelprojectopen)
+
+#include "tst_elementspanelprojectopen.moc"