diff --git a/src/Gui/ApplicationPy.cpp b/src/Gui/ApplicationPy.cpp
index 7d79cf13b2..3044161ede 100644
--- a/src/Gui/ApplicationPy.cpp
+++ b/src/Gui/ApplicationPy.cpp
@@ -831,7 +831,7 @@ PyObject* Application::sSendActiveView(PyObject * /*self*/, PyObject *args)
 
     const char* ppReturn = nullptr;
     if (!Instance->sendMsgToActiveView(psCommandStr,&ppReturn)) {
-        if (!PyObject_IsTrue(suppress))
+        if (PyObject_IsTrue(suppress) ? false : true)
             Base::Console().Warning("Unknown view command: %s\n",psCommandStr);
     }
 
@@ -852,7 +852,7 @@ PyObject* Application::sSendFocusView(PyObject * /*self*/, PyObject *args)
 
     const char* ppReturn = nullptr;
     if (!Instance->sendMsgToFocusView(psCommandStr,&ppReturn)) {
-        if (!PyObject_IsTrue(suppress))
+        if (PyObject_IsTrue(suppress) ? false : true)
             Base::Console().Warning("Unknown view command: %s\n",psCommandStr);
     }
 
diff --git a/src/Gui/CommandPyImp.cpp b/src/Gui/CommandPyImp.cpp
index 9a8b07fe6b..73745d5f9e 100644
--- a/src/Gui/CommandPyImp.cpp
+++ b/src/Gui/CommandPyImp.cpp
@@ -92,14 +92,14 @@ PyObject* CommandPy::listByShortcut(PyObject *args)
 
     std::vector <Command*> cmds = Application::Instance->commandManager().getAllCommands();
     std::vector <std::string> matches;
-    for (Command* c : cmds){
+    for (Command* c : cmds) {
         Action* action = c->getAction();
-        if (action){
+        if (action) {
             QString spc = QString::fromLatin1(" ");
-            if(PyObject_IsTrue(bIsRegularExp)){
+            if (PyObject_IsTrue(bIsRegularExp) ? true : false) {
                QRegExp re = QRegExp(QString::fromLatin1(shortcut_to_find));
                re.setCaseSensitivity(Qt::CaseInsensitive);
-               if (!re.isValid()){
+               if (!re.isValid()) {
                    std::stringstream str;
                    str << "Invalid regular expression:" << ' ' << shortcut_to_find;
                    throw Py::RuntimeError(str.str());
diff --git a/src/Gui/LinkViewPyImp.cpp b/src/Gui/LinkViewPyImp.cpp
index 735a44841c..07468c4a2c 100644
--- a/src/Gui/LinkViewPyImp.cpp
+++ b/src/Gui/LinkViewPyImp.cpp
@@ -171,11 +171,11 @@ PyObject* LinkViewPy::setTransform(PyObject *args) {
 PyObject* LinkViewPy::setType(PyObject *args) {
     short type;
     PyObject *sublink = Py_True;
-    if (!PyArg_ParseTuple(args, "h|O", &type,&sublink))
+    if (!PyArg_ParseTuple(args, "h|O!", &type, &PyBool_Type, &sublink))
         return nullptr;
 
     PY_TRY{
-        getLinkViewPtr()->setNodeType((LinkView::SnapshotType)type,PyObject_IsTrue(sublink));
+        getLinkViewPtr()->setNodeType((LinkView::SnapshotType)type, PyObject_IsTrue(sublink) ? true : false);
         Py_Return;
     } PY_CATCH;
 }
diff --git a/src/Gui/MDIViewPy.cpp b/src/Gui/MDIViewPy.cpp
index a630a5a13a..168f4cf788 100644
--- a/src/Gui/MDIViewPy.cpp
+++ b/src/Gui/MDIViewPy.cpp
@@ -258,7 +258,7 @@ Py::Object MDIViewPy::getActiveObject(const Py::Tuple& args)
 {
     const char* name;
     PyObject *resolve = Py_True;
-    if (!PyArg_ParseTuple(args.ptr(), "s|O", &name,&resolve))
+    if (!PyArg_ParseTuple(args.ptr(), "s|O!", &name, &PyBool_Type, &resolve))
         throw Py::Exception();
 
     App::DocumentObject *parent = nullptr;
@@ -269,7 +269,7 @@ Py::Object MDIViewPy::getActiveObject(const Py::Tuple& args)
     if (!obj)
         return Py::None();
 
-    if (PyObject_IsTrue(resolve))
+    if (PyObject_IsTrue(resolve) ? true : false)
         return Py::asObject(obj->getPyObject());
 
     return Py::TupleN(
diff --git a/src/Gui/Selection.cpp b/src/Gui/Selection.cpp
index 9d2d3d6f51..63b15d6a12 100644
--- a/src/Gui/Selection.cpp
+++ b/src/Gui/Selection.cpp
@@ -2072,7 +2072,7 @@ PyObject *SelectionSingleton::sAddSelection(PyObject * /*self*/, PyObject *args)
     float x = 0, y = 0, z = 0;
     if (PyArg_ParseTuple(args, "ss|sfffO!", &docname, &objname ,
                 &subname,&x,&y,&z,&PyBool_Type,&clearPreselect)) {
-        Selection().addSelection(docname,objname,subname,x,y,z,nullptr,PyObject_IsTrue(clearPreselect));
+        Selection().addSelection(docname,objname,subname,x,y,z,nullptr,PyObject_IsTrue(clearPreselect) ? true : false);
         Py_Return;
     }
 
@@ -2091,7 +2091,7 @@ PyObject *SelectionSingleton::sAddSelection(PyObject * /*self*/, PyObject *args)
 
         Selection().addSelection(docObj->getDocument()->getName(),
                                  docObj->getNameInDocument(),
-                                 subname,x,y,z,nullptr,PyObject_IsTrue(clearPreselect));
+                                 subname,x,y,z,nullptr,PyObject_IsTrue(clearPreselect) ? true : false);
         Py_Return;
     }
 
@@ -2114,7 +2114,7 @@ PyObject *SelectionSingleton::sAddSelection(PyObject * /*self*/, PyObject *args)
                     std::string subname = static_cast<std::string>(Py::String(*it));
                     Selection().addSelection(docObj->getDocument()->getName(),
                                              docObj->getNameInDocument(),
-                                             subname.c_str(),0,0,0,nullptr,PyObject_IsTrue(clearPreselect));
+                                             subname.c_str(),0,0,0,nullptr,PyObject_IsTrue(clearPreselect) ? true : false);
                 }
 
                 Py_Return;
@@ -2146,7 +2146,7 @@ PyObject *SelectionSingleton::sUpdateSelection(PyObject * /*self*/, PyObject *ar
         return nullptr;
     }
 
-    Selection().updateSelection(PyObject_IsTrue(show),
+    Selection().updateSelection(PyObject_IsTrue(show) ? true : false,
             docObj->getDocument()->getName(), docObj->getNameInDocument(), subname);
 
     Py_Return;
@@ -2193,7 +2193,7 @@ PyObject *SelectionSingleton::sClearSelection(PyObject * /*self*/, PyObject *arg
         if (!PyArg_ParseTuple(args, "|sO!", &documentName, &PyBool_Type, &clearPreSelect))
             return nullptr;
     }
-    Selection().clearSelection(documentName,PyObject_IsTrue(clearPreSelect));
+    Selection().clearSelection(documentName,PyObject_IsTrue(clearPreSelect) ? true : false);
 
     Py_Return;
 }
@@ -2263,7 +2263,7 @@ PyObject *SelectionSingleton::sGetSelection(PyObject * /*self*/, PyObject *args)
 
     try {
         std::vector<SelectionSingleton::SelObj> sel;
-        sel = Selection().getSelection(documentName, toEnum(resolve), PyObject_IsTrue(single));
+        sel = Selection().getSelection(documentName, toEnum(resolve), PyObject_IsTrue(single) ? true : false);
 
         std::set<App::DocumentObject*> noduplicates;
         std::vector<App::DocumentObject*> selectedObjects; // keep the order of selection
@@ -2293,7 +2293,7 @@ PyObject *SelectionSingleton::sEnablePickedList(PyObject * /*self*/, PyObject *a
     if (!PyArg_ParseTuple(args, "|O!", &PyBool_Type, &enable))
         return nullptr;
 
-    Selection().enablePickedList(PyObject_IsTrue(enable));
+    Selection().enablePickedList(PyObject_IsTrue(enable) ? true : false);
 
     Py_Return;
 }
@@ -2382,7 +2382,7 @@ PyObject *SelectionSingleton::sGetSelectionEx(PyObject * /*self*/, PyObject *arg
     try {
         std::vector<SelectionObject> sel;
         sel = Selection().getSelectionEx(documentName,
-                App::DocumentObject::getClassTypeId(), toEnum(resolve), PyObject_IsTrue(single));
+                App::DocumentObject::getClassTypeId(), toEnum(resolve), PyObject_IsTrue(single) ? true : false);
 
         Py::List list;
         for (std::vector<SelectionObject>::iterator it = sel.begin(); it != sel.end(); ++it) {
@@ -2563,7 +2563,7 @@ PyObject *SelectionSingleton::sPushSelStack(PyObject * /*self*/, PyObject *args)
     if (!PyArg_ParseTuple(args, "|O!O!", &PyBool_Type, &clear, &PyBool_Type, &overwrite))
         return nullptr;
 
-    Selection().selStackPush(PyObject_IsTrue(clear), PyObject_IsTrue(overwrite));
+    Selection().selStackPush(PyObject_IsTrue(clear), PyObject_IsTrue(overwrite) ? true : false);
 
     Py_Return;
 }
@@ -2596,7 +2596,7 @@ PyObject *SelectionSingleton::sHasSubSelection(PyObject * /*self*/, PyObject *ar
 
     PY_TRY {
         return Py::new_reference_to(
-                Py::Boolean(Selection().hasSubSelection(doc,PyObject_IsTrue(subElement))));
+                Py::Boolean(Selection().hasSubSelection(doc,PyObject_IsTrue(subElement) ? true : false)));
     }
     PY_CATCH;
 }
diff --git a/src/Gui/View3DPy.cpp b/src/Gui/View3DPy.cpp
index 35f6b462b0..ad8bf4ec94 100644
--- a/src/Gui/View3DPy.cpp
+++ b/src/Gui/View3DPy.cpp
@@ -885,13 +885,13 @@ Py::Object View3DInventorPy::setCameraOrientation(const Py::Tuple& args)
             float q1 = (float)Py::Float(tuple[1]);
             float q2 = (float)Py::Float(tuple[2]);
             float q3 = (float)Py::Float(tuple[3]);
-            getView3DIventorPtr()->getViewer()->setCameraOrientation(SbRotation(q0, q1, q2, q3), PyObject_IsTrue(m));
+            getView3DIventorPtr()->getViewer()->setCameraOrientation(SbRotation(q0, q1, q2, q3), PyObject_IsTrue(m) ? true : false);
         }
         else if (PyObject_TypeCheck(o, &Base::RotationPy::Type)) {
             Base::Rotation r = (Base::Rotation)Py::Rotation(o,false);
             double q0, q1, q2, q3;
             r.getValue(q0, q1, q2, q3);
-            getView3DIventorPtr()->getViewer()->setCameraOrientation(SbRotation((float)q0, (float)q1, (float)q2, (float)q3), PyObject_IsTrue(m));
+            getView3DIventorPtr()->getViewer()->setCameraOrientation(SbRotation((float)q0, (float)q1, (float)q2, (float)q3), PyObject_IsTrue(m) ? true : false);
         }
         else {
             throw Py::ValueError("Neither tuple nor rotation object");
@@ -1293,11 +1293,11 @@ Py::Object View3DInventorPy::dump(const Py::Tuple& args)
 {
     char* filename;
     PyObject *onlyVisible = Py_False;
-    if (!PyArg_ParseTuple(args.ptr(), "s|O", &filename, &onlyVisible))
+    if (!PyArg_ParseTuple(args.ptr(), "s|O!", &filename, &PyBool_Type, &onlyVisible))
         throw Py::Exception();
 
     try {
-        getView3DIventorPtr()->dump(filename, PyObject_IsTrue(onlyVisible));
+        getView3DIventorPtr()->dump(filename, PyObject_IsTrue(onlyVisible) ? true : false);
         return Py::None();
     }
     catch (const Base::Exception& e) {
@@ -2583,7 +2583,7 @@ Py::Object View3DInventorPy::getActiveObject(const Py::Tuple& args)
 {
     char* name;
     PyObject *resolve = Py_True;
-    if (!PyArg_ParseTuple(args.ptr(), "s|O", &name,&resolve))
+    if (!PyArg_ParseTuple(args.ptr(), "s|O!", &name, &PyBool_Type, &resolve))
                 throw Py::Exception();
 
     App::DocumentObject *parent = nullptr;
@@ -2592,7 +2592,7 @@ Py::Object View3DInventorPy::getActiveObject(const Py::Tuple& args)
     if (!obj)
         return Py::None();
 
-    if (PyObject_IsTrue(resolve))
+    if (PyObject_IsTrue(resolve) ? true : false)
         return Py::asObject(obj->getPyObject());
 
     return Py::TupleN(
@@ -2652,15 +2652,16 @@ Py::Object View3DInventorPy::toggleClippingPlane(const Py::Tuple& args, const Py
     PyObject *beforeEditing = Py_False;
     PyObject *noManip = Py_True;
     PyObject *pyPla = Py_None;
-    if (!PyArg_ParseTupleAndKeywords(args.ptr(), kwds.ptr(), "|iOOO!", keywords,
-                    &toggle, &beforeEditing, &noManip, &Base::PlacementPy::Type,&pyPla))
+    if (!PyArg_ParseTupleAndKeywords(args.ptr(), kwds.ptr(), "|iO!O!O!", keywords,
+                    &toggle, &PyBool_Type, &beforeEditing, &PyBool_Type, &noManip,
+                    &Base::PlacementPy::Type, &pyPla))
         throw Py::Exception();
 
     Base::Placement pla;
     if(pyPla!=Py_None)
         pla = *static_cast<Base::PlacementPy*>(pyPla)->getPlacementPtr();
-    getView3DIventorPtr()->getViewer()->toggleClippingPlane(toggle,PyObject_IsTrue(beforeEditing),
-            PyObject_IsTrue(noManip),pla);
+    getView3DIventorPtr()->getViewer()->toggleClippingPlane(toggle,PyObject_IsTrue(beforeEditing) ? true : false,
+            PyObject_IsTrue(noManip) ? true : false,pla);
     return Py::None();
 }
 
diff --git a/src/Gui/View3DViewerPy.cpp b/src/Gui/View3DViewerPy.cpp
index 51d568573e..9d769d57bd 100644
--- a/src/Gui/View3DViewerPy.cpp
+++ b/src/Gui/View3DViewerPy.cpp
@@ -410,11 +410,11 @@ Py::Object View3DInventorViewerPy::setupEditingRoot(const Py::Tuple& args)
 Py::Object View3DInventorViewerPy::resetEditingRoot(const Py::Tuple& args)
 {
     PyObject *updateLinks = Py_True;
-    if (!PyArg_ParseTuple(args.ptr(), "|O", &updateLinks)) {
+    if (!PyArg_ParseTuple(args.ptr(), "|O!", &PyBool_Type, &updateLinks)) {
         throw Py::Exception();
     }
     try {
-        _viewer->resetEditingRoot(PyObject_IsTrue(updateLinks));
+        _viewer->resetEditingRoot(PyObject_IsTrue(updateLinks) ? true : false);
         return Py::None();
     }
     catch (const Base::Exception& e) {
@@ -473,7 +473,7 @@ Py::Object View3DInventorViewerPy::setEnabledNaviCube(const Py::Tuple& args)
     PyObject* m=Py_False;
     if (!PyArg_ParseTuple(args.ptr(), "O!", &PyBool_Type, &m))
         throw Py::Exception();
-    _viewer->setEnabledNaviCube(PyObject_IsTrue(m));
+    _viewer->setEnabledNaviCube(PyObject_IsTrue(m) ? true : false);
     return Py::None();
 }
 
diff --git a/src/Gui/ViewProviderPyImp.cpp b/src/Gui/ViewProviderPyImp.cpp
index 757ae7aeb5..09b7e57930 100644
--- a/src/Gui/ViewProviderPyImp.cpp
+++ b/src/Gui/ViewProviderPyImp.cpp
@@ -532,7 +532,7 @@ PyObject *ViewProviderPy::getBoundingBox(PyObject *args) {
         View3DInventor *view = nullptr;
         if(pyView)
             view = static_cast<View3DInventorPy*>(pyView)->getView3DIventorPtr();
-        auto bbox = getViewProviderPtr()->getBoundingBox(subname,PyObject_IsTrue(transform),view);
+        auto bbox = getViewProviderPtr()->getBoundingBox(subname,PyObject_IsTrue(transform) ? true : false,view);
         return new Base::BoundBoxPy(new Base::BoundBox3d(bbox));
     }
     PY_CATCH;