diff --git a/forms/source/component/EventThread.cxx b/forms/source/component/EventThread.cxx
index 2d5336fe384b..62b0af091c8f 100644
--- a/forms/source/component/EventThread.cxx
+++ b/forms/source/component/EventThread.cxx
@@ -76,11 +76,11 @@ void OComponentEventThread::impl_clearEventQueue()
 
 void OComponentEventThread::disposing( const EventObject& evt )
 {
+    std::unique_lock aGuard( m_aMutex );
+
     if( evt.Source != static_cast<XWeak*>(m_xComp.get()) )
         return;
 
-    std::unique_lock aGuard( m_aMutex );
-
     // Remove EventListener
     Reference<XEventListener>  xEvtLstnr = static_cast<XEventListener*>(this);
     m_xComp->removeEventListener( xEvtLstnr );