diff --git a/src/calibre/gui2/viewer/toc.py b/src/calibre/gui2/viewer/toc.py
index 42cedcb66a..327a5363cf 100644
--- a/src/calibre/gui2/viewer/toc.py
+++ b/src/calibre/gui2/viewer/toc.py
@@ -24,7 +24,7 @@ class TOCView(QTreeView):
                     border: none;
                 }
                 QTreeView::item {
-                    border: none;
+                    border: 1px solid transparent;
                     padding-top:0.5ex;
                     padding-bottom:0.5ex;
                 }