diff --git a/src/GUI.cpp b/src/GUI.cpp
index 253bb4f59..bc2a40359 100644
--- a/src/GUI.cpp
+++ b/src/GUI.cpp
@@ -452,6 +452,7 @@ void GUI::displayInfoBarMenu(const QPoint& pos){
 
 void GUI::sortProgressColumnDelayed() {
     if(delayedSorting){
+      QMutexLocker lock(&DLListAccess);
       sortDownloadListFloat(PROGRESS, delayedSortingOrder);
       qDebug("Delayed sorting of progress column");
       delayedSorting = false;