diff --git a/src/Mod/Fem/Gui/TaskFemConstraint.h b/src/Mod/Fem/Gui/TaskFemConstraint.h
index 2dab3c55d0..2474347fbe 100644
--- a/src/Mod/Fem/Gui/TaskFemConstraint.h
+++ b/src/Mod/Fem/Gui/TaskFemConstraint.h
@@ -25,9 +25,10 @@
 #ifndef GUI_TASKVIEW_TaskFemConstraint_H
 #define GUI_TASKVIEW_TaskFemConstraint_H
 
-#include <Gui/TaskView/TaskView.h>
+#include <Gui/DocumentObserver.h>
 #include <Gui/Selection.h>
 #include <Gui/TaskView/TaskDialog.h>
+#include <Gui/TaskView/TaskView.h>
 
 #include "ViewProviderFemConstraint.h"
 
@@ -69,7 +70,7 @@ protected:
 protected:
     QWidget* proxy;
     QAction* deleteAction;
-    ViewProviderFemConstraint *ConstraintView;
+    Gui::WeakPtrT<ViewProviderFemConstraint> ConstraintView;
     enum {seldir, selref, selloc, selnone} selectionMode;
 
 private:
diff --git a/src/Mod/Fem/Gui/TaskFemConstraintOnBoundary.cpp b/src/Mod/Fem/Gui/TaskFemConstraintOnBoundary.cpp
index b85f91db73..a57fca6e4b 100644
--- a/src/Mod/Fem/Gui/TaskFemConstraintOnBoundary.cpp
+++ b/src/Mod/Fem/Gui/TaskFemConstraintOnBoundary.cpp
@@ -39,7 +39,8 @@ TaskFemConstraintOnBoundary::TaskFemConstraintOnBoundary(ViewProviderFemConstrai
 
 TaskFemConstraintOnBoundary::~TaskFemConstraintOnBoundary()
 {
-    ConstraintView->highlightReferences(false);
+    if (!ConstraintView.expired())
+        ConstraintView->highlightReferences(false);
 }
 
 void TaskFemConstraintOnBoundary::_addToSelection(bool checked)