diff --git a/vcl/source/uitest/uno/uiobject_uno.cxx b/vcl/source/uitest/uno/uiobject_uno.cxx
index 7c6ca8398b90..6506c058fd6f 100644
--- a/vcl/source/uitest/uno/uiobject_uno.cxx
+++ b/vcl/source/uitest/uno/uiobject_uno.cxx
@@ -20,6 +20,8 @@ UIObjectUnoObj::UIObjectUnoObj(std::unique_ptr<UIObject> pObj):
 
 UIObjectUnoObj::~UIObjectUnoObj()
 {
+    SolarMutexGuard aGuard;
+    mpObj.reset();
 }
 
 css::uno::Reference<css::ui::test::XUIObject> SAL_CALL UIObjectUnoObj::getChild(const OUString& rID)