diff --git a/src/Mod/Sketcher/Gui/CommandCreateGeo.cpp b/src/Mod/Sketcher/Gui/CommandCreateGeo.cpp
index 2ab3262f76..b6c68f8f44 100644
--- a/src/Mod/Sketcher/Gui/CommandCreateGeo.cpp
+++ b/src/Mod/Sketcher/Gui/CommandCreateGeo.cpp
@@ -215,6 +215,7 @@ void removeRedundantHorizontalVertical(Sketcher::SketchObject* psketch,
             for(std::vector<AutoConstraint>::reverse_iterator it = sug2.rbegin(); it!=sug2.rend(); ++it) {
                 if( (*it).Type == Sketcher::Horizontal || (*it).Type == Sketcher::Vertical) {
                     sug2.erase(std::next(it).base());
+                    it = sug2.rbegin(); // erase invalidates the iterator
                 }
             }
         }
@@ -348,13 +349,13 @@ public:
                 removeRedundantHorizontalVertical(static_cast<Sketcher::SketchObject *>(sketchgui->getObject()),sugConstr1,sugConstr2);
 
             // add auto constraints for the line segment start
-            if (sugConstr1.size() > 0) {
+            if (!sugConstr1.empty()) {
                 createAutoConstraints(sugConstr1, getHighestCurveIndex(), Sketcher::start);
                 sugConstr1.clear();
             }
 
             // add auto constraints for the line segment end
-            if (sugConstr2.size() > 0) {
+            if (!sugConstr2.empty()) {
                 createAutoConstraints(sugConstr2, getHighestCurveIndex(), Sketcher::end);
                 sugConstr2.clear();
             }
diff --git a/src/Mod/Sketcher/Gui/TaskSketcherGeneral.cpp b/src/Mod/Sketcher/Gui/TaskSketcherGeneral.cpp
index 9981a30597..8b75462ed3 100644
--- a/src/Mod/Sketcher/Gui/TaskSketcherGeneral.cpp
+++ b/src/Mod/Sketcher/Gui/TaskSketcherGeneral.cpp
@@ -56,8 +56,6 @@ SketcherGeneralWidget::SketcherGeneralWidget(QWidget *parent)
             this, SIGNAL(emitToggleAutoconstraints(int)));
     connect(ui->renderingOrder->model(), SIGNAL(layoutChanged()),
             this, SLOT(renderOrderChanged()));
-    connect(ui->checkBoxRedundantAutoconstraints, SIGNAL(stateChanged(int)),
-            this, SLOT(on_checkBoxRedundantAutoconstraints_stateChanged(int)));
 }
 
 SketcherGeneralWidget::~SketcherGeneralWidget()
@@ -159,7 +157,7 @@ void SketcherGeneralWidget::renderOrderChanged()
     emitRenderOrderChanged();
 }
 
-void SketcherGeneralWidget::on_checkBoxRedundantAutoconstraints_stateChanged(int state)
+void SketcherGeneralWidget::on_checkBoxRedundantAutoconstraints_stateChanged(int /*state*/)
 {
     ui->checkBoxRedundantAutoconstraints->onSave();
 }