--- a/libmolsketch/molscene.cpp
+++ b/libmolsketch/molscene.cpp
@@ -842,7 +842,7 @@
   void MolScene::dragEnterEvent(QGraphicsSceneDragDropEvent *event)
   {
     if (!event->mimeData() || !event->mimeData()->hasFormat(mimeType())) return;
-    if (!event->proposedAction() == Qt::CopyAction) return;
+    if ((!event->proposedAction()) == Qt::CopyAction) return;
     event->accept();
     for (genericAction* action : sceneActions())
       action->setChecked(false);