diff --git a/src/Mod/TechDraw/App/DrawProjGroupPyImp.cpp b/src/Mod/TechDraw/App/DrawProjGroupPyImp.cpp
index 0100bf27c..a77b75e5c 100644
--- a/src/Mod/TechDraw/App/DrawProjGroupPyImp.cpp
+++ b/src/Mod/TechDraw/App/DrawProjGroupPyImp.cpp
@@ -21,7 +21,7 @@ std::string DrawProjGroupPy::representation(void) const
 
 PyObject* DrawProjGroupPy::addProjection(PyObject* args)
 {
-    const char* projType;
+    char* projType;
 
     if (!PyArg_ParseTuple(args, "s", &projType)) {
         throw Py::Exception();
@@ -30,13 +30,17 @@ PyObject* DrawProjGroupPy::addProjection(PyObject* args)
     DrawProjGroup* projGroup = getDrawProjGroupPtr();
     App::DocumentObject* docObj = projGroup->addProjection(projType);
     TechDraw::DrawProjGroupItem* newProj = dynamic_cast<TechDraw::DrawProjGroupItem *>( docObj );
+    if (!newProj) {
+        PyErr_SetString(PyExc_TypeError, "wrong type for adding projection");
+        return nullptr;
+    }
 
     return new DrawProjGroupItemPy(newProj);
 }
 
 PyObject* DrawProjGroupPy::removeProjection(PyObject* args)
 {
-    const char* projType;
+    char* projType;
 
     if (!PyArg_ParseTuple(args, "s", &projType)) {
         throw Py::Exception();
@@ -45,7 +49,7 @@ PyObject* DrawProjGroupPy::removeProjection(PyObject* args)
     DrawProjGroup* projGroup = getDrawProjGroupPtr();
     int i = projGroup->removeProjection(projType);
 
-    return PyInt_FromLong((long) i);;
+    return PyInt_FromLong((long) i);
 }
 
 PyObject* DrawProjGroupPy::purgeProjections(PyObject* /*args*/)
@@ -53,12 +57,12 @@ PyObject* DrawProjGroupPy::purgeProjections(PyObject* /*args*/)
     DrawProjGroup* projGroup = getDrawProjGroupPtr();
     int i = projGroup->purgeProjections();
 
-    return PyInt_FromLong((long) i);;
+    return PyInt_FromLong((long) i);
 }
 
 PyObject* DrawProjGroupPy::getItemByLabel(PyObject* args)
 {
-    const char* projType;
+    char* projType;
 
     if (!PyArg_ParseTuple(args, "s", &projType)) {
         throw Py::Exception();
@@ -67,6 +71,10 @@ PyObject* DrawProjGroupPy::getItemByLabel(PyObject* args)
     DrawProjGroup* projGroup = getDrawProjGroupPtr();
     App::DocumentObject* docObj = projGroup->getProjObj(projType);
     TechDraw::DrawProjGroupItem* newProj = dynamic_cast<TechDraw::DrawProjGroupItem *>( docObj );
+    if (!newProj) {
+        PyErr_SetString(PyExc_TypeError, "wrong type for getting item");
+        return nullptr;
+    }
 
     return new DrawProjGroupItemPy(newProj);
 }
@@ -74,7 +82,7 @@ PyObject* DrawProjGroupPy::getItemByLabel(PyObject* args)
 //TODO: this is no longer required?
 PyObject* DrawProjGroupPy::setViewOrientation(PyObject* args)
 {
-    const char* projType;
+    char* projType;
     PyObject* pcObj;
     if (!PyArg_ParseTuple(args, "Os", &pcObj,&projType))
         throw Py::Exception();
diff --git a/src/Mod/TechDraw/Gui/QGIViewImage.cpp b/src/Mod/TechDraw/Gui/QGIViewImage.cpp
index d441fcfb2..78596c355 100644
--- a/src/Mod/TechDraw/Gui/QGIViewImage.cpp
+++ b/src/Mod/TechDraw/Gui/QGIViewImage.cpp
@@ -112,7 +112,7 @@ void QGIViewImage::draw()
         return;
     }
 
-    auto viewImage( dynamic_cast<TechDraw::DrawViewImage*>(getViewObject()) );
+    auto viewImage( static_cast<TechDraw::DrawViewImage*>(getViewObject()) );
     QRectF newRect(0.0,0.0,viewImage->Width.getValue(),viewImage->Height.getValue());
     m_cliparea->setRect(newRect.adjusted(-1,-1,1,1));
 
diff --git a/src/Mod/TechDraw/Gui/QGIViewPart.cpp b/src/Mod/TechDraw/Gui/QGIViewPart.cpp
index 4e49dc45a..61507e362 100644
--- a/src/Mod/TechDraw/Gui/QGIViewPart.cpp
+++ b/src/Mod/TechDraw/Gui/QGIViewPart.cpp
@@ -615,7 +615,7 @@ void QGIViewPart::drawMatting()
 {
     auto viewPart( dynamic_cast<TechDraw::DrawViewPart *>(getViewObject()) );
     TechDraw::DrawViewDetail* dvd = nullptr;
-    if (viewPart->isDerivedFrom(TechDraw::DrawViewDetail::getClassTypeId())) {
+    if (viewPart && viewPart->isDerivedFrom(TechDraw::DrawViewDetail::getClassTypeId())) {
         dvd = static_cast<TechDraw::DrawViewDetail*>(viewPart);
     } else {
         return;
diff --git a/src/Mod/TechDraw/Gui/TaskLinkDim.cpp b/src/Mod/TechDraw/Gui/TaskLinkDim.cpp
index bd822b7cb..0688e49a8 100644
--- a/src/Mod/TechDraw/Gui/TaskLinkDim.cpp
+++ b/src/Mod/TechDraw/Gui/TaskLinkDim.cpp
@@ -108,7 +108,7 @@ void TaskLinkDim::loadAvailDims()
     int found = 0;
     for (; itView != pageViews.end(); itView++) {
         if ((*itView)->isDerivedFrom(TechDraw::DrawViewDimension::getClassTypeId())) {
-            TechDraw::DrawViewDimension* dim = dynamic_cast<TechDraw::DrawViewDimension*>((*itView));
+            TechDraw::DrawViewDimension* dim = static_cast<TechDraw::DrawViewDimension*>((*itView));
             int dimRefType = dim->getRefType();
             if (dimRefType == selRefType) {                                     //potential matches
                 found++;
@@ -190,7 +190,6 @@ bool TaskLinkDim::dimReferencesSelection(const TechDraw::DrawViewDimension* dim)
 
 void TaskLinkDim::updateDims()
 {
-
     int iDim;
     int count = ui->selector->selectedTreeWidget()->topLevelItemCount();
     for (iDim=0; iDim<count; iDim++) {
@@ -198,6 +197,8 @@ void TaskLinkDim::updateDims()
         QString name = child->data(0, Qt::UserRole).toString();
         App::DocumentObject* obj = m_page->getDocument()->getObject(name.toStdString().c_str());
         TechDraw::DrawViewDimension* dim = dynamic_cast<TechDraw::DrawViewDimension*>(obj);
+        if (!dim)
+            continue;
 //        std::vector<App::DocumentObject*> parts;
 //        for (unsigned int iPart = 0; iPart < m_subs.size(); iPart++) {
 //            parts.push_back(m_part);
@@ -215,7 +216,7 @@ void TaskLinkDim::updateDims()
         QString name = child->data(0, Qt::UserRole).toString();
         App::DocumentObject* obj = m_page->getDocument()->getObject(name.toStdString().c_str());
         TechDraw::DrawViewDimension* dim = dynamic_cast<TechDraw::DrawViewDimension*>(obj);
-        if (dimReferencesSelection(dim))  {
+        if (dim && dimReferencesSelection(dim))  {
            std::string measureType = "Projected";
            std::string DimName = dim->getNameInDocument();
            Gui::Command::doCommand(Gui::Command::Gui,"App.activeDocument().%s.MeasureType = \'%s\'",
diff --git a/src/Mod/TechDraw/Gui/TaskProjGroup.cpp b/src/Mod/TechDraw/Gui/TaskProjGroup.cpp
index 9d8d105cc..8d7cdf6cd 100644
--- a/src/Mod/TechDraw/Gui/TaskProjGroup.cpp
+++ b/src/Mod/TechDraw/Gui/TaskProjGroup.cpp
@@ -111,7 +111,7 @@ TaskProjGroup::TaskProjGroup(TechDraw::DrawProjGroup* featView, bool mode) :
     m_page = multiView->findParentPage();
     Gui::Document* activeGui = Gui::Application::Instance->getDocument(m_page->getDocument());
     Gui::ViewProvider* vp = activeGui->getViewProvider(m_page);
-    ViewProviderPage* dvp = dynamic_cast<ViewProviderPage*>(vp);
+    ViewProviderPage* dvp = static_cast<ViewProviderPage*>(vp);
     m_mdi = dvp->getMDIViewPage();
 
     setUiPrimary();