=== modified file 'src/sp-item.cpp'
--- src/sp-item.cpp	2016-08-03 14:56:48 +0000
+++ src/sp-item.cpp	2016-09-06 15:01:21 +0000
@@ -326,7 +326,9 @@
 void SPItem::lowerToBottom() {
     auto bottom = std::find_if(parent->children.begin(), parent->children.iterator_to(*this), &is_item);
     if (bottom != parent->children.iterator_to(*this)) {
-        bottom--;
+        if (bottom != parent->children.begin()) {
+            bottom--;
+        }
         Inkscape::XML::Node *ref = bottom->getRepr() ;
         parent->getRepr()->changeOrder(getRepr(), ref);
     }