diff --git a/sw/source/ui/dbui/customizeaddresslistdialog.cxx b/sw/source/ui/dbui/customizeaddresslistdialog.cxx
index cd1a2acc2893..68d38a45ed79 100644
--- a/sw/source/ui/dbui/customizeaddresslistdialog.cxx
+++ b/sw/source/ui/dbui/customizeaddresslistdialog.cxx
@@ -121,7 +121,7 @@ IMPL_LINK_NOARG(SwCustomizeAddressListDialog, DeleteHdl_Impl, weld::Button&, voi
 IMPL_LINK(SwCustomizeAddressListDialog, UpDownHdl_Impl, weld::Button&, rButton, void)
 {
     auto nPos = m_xFieldsLB->get_selected_index();
-    assert(nPos && "nothing selected");
+    assert(nPos != -1 && "nothing selected");
     auto nOldPos = nPos;
     OUString aTemp = m_xFieldsLB->get_text(nPos);
     m_xFieldsLB->remove(nPos);
diff --git a/sw/source/uibase/utlui/glbltree.cxx b/sw/source/uibase/utlui/glbltree.cxx
index 6553f8e3d778..35aa93c8ad51 100644
--- a/sw/source/uibase/utlui/glbltree.cxx
+++ b/sw/source/uibase/utlui/glbltree.cxx
@@ -398,6 +398,12 @@ void SwGlobalTree::MoveSelectionTo(const weld::TreeIter* pDropEntry)
 {
     int nSource = m_xTreeView->get_selected_index();
 
+    if (nSource == -1)
+    {
+        SAL_WARN("sw", "No selection to move");
+        return;
+    }
+
     int nDest = pDropEntry ? m_xTreeView->get_iter_index_in_parent(*pDropEntry)
                            : m_pSwGlblDocContents->size();