diff --git a/src/torrentfilesmodel.h b/src/torrentfilesmodel.h
index 048b8034b..fd9e1bb56 100644
--- a/src/torrentfilesmodel.h
+++ b/src/torrentfilesmodel.h
@@ -136,6 +136,7 @@ public:
 
   void setProgress(float progress) {
     if(progress == getProgress()) return;
+    Q_ASSERT(progress >= 0. && progress <= 1.);
     itemData.replace(2, progress);
     if(parentItem)
       parentItem->updateProgress();