diff --git a/src/Gui/Tree.cpp b/src/Gui/Tree.cpp
index 03ca7cb2f..2c5f0ea15 100644
--- a/src/Gui/Tree.cpp
+++ b/src/Gui/Tree.cpp
@@ -440,20 +440,39 @@ void TreeWidget::dropEvent(QDropEvent *event)
                 ::getGroupOfObject(obj);
             if (par) {
                 // allow an object to be in one group only
-                QString cmd = QString::fromAscii("App.getDocument(\"%1\").getObject(\"%2\").removeObject("
+                QString cmd;
+                if (par->getTypeId().isDerivedFrom(App::DocumentObjectGroupPython::getClassTypeId())) {
+                    // if this is a python group, call the method of its Proxy
+                    cmd = QString::fromAscii("App.getDocument(\"%1\").getObject(\"%2\").Proxy.removeObject("
                                       "App.getDocument(\"%1\").getObject(\"%3\"))")
                                       .arg(QString::fromAscii(doc->getName()))
                                       .arg(QString::fromAscii(par->getNameInDocument()))
                                       .arg(QString::fromAscii(obj->getNameInDocument()));
+                } else {
+                    cmd = QString::fromAscii("App.getDocument(\"%1\").getObject(\"%2\").removeObject("
+                                      "App.getDocument(\"%1\").getObject(\"%3\"))")
+                                      .arg(QString::fromAscii(doc->getName()))
+                                      .arg(QString::fromAscii(par->getNameInDocument()))
+                                      .arg(QString::fromAscii(obj->getNameInDocument()));
+                }
                 Gui::Application::Instance->runPythonCode(cmd.toUtf8());
             }
 
             // build Python command for execution
-            QString cmd = QString::fromAscii("App.getDocument(\"%1\").getObject(\"%2\").addObject("
+            QString cmd;
+            if (grp->getTypeId().isDerivedFrom(App::DocumentObjectGroupPython::getClassTypeId())) {
+                cmd = QString::fromAscii("App.getDocument(\"%1\").getObject(\"%2\").Proxy.addObject("
                                   "App.getDocument(\"%1\").getObject(\"%3\"))")
                                   .arg(QString::fromAscii(doc->getName()))
                                   .arg(QString::fromAscii(grp->getNameInDocument()))
                                   .arg(QString::fromAscii(obj->getNameInDocument()));
+            } else {
+                cmd = QString::fromAscii("App.getDocument(\"%1\").getObject(\"%2\").addObject("
+                                  "App.getDocument(\"%1\").getObject(\"%3\"))")
+                                  .arg(QString::fromAscii(doc->getName()))
+                                  .arg(QString::fromAscii(grp->getNameInDocument()))
+                                  .arg(QString::fromAscii(obj->getNameInDocument()));
+            }
             Gui::Application::Instance->runPythonCode(cmd.toUtf8());
         }
         gui->commitCommand();