diff --git a/src/OpenGl/OpenGl_GraphicDriver_1.cxx b/src/OpenGl/OpenGl_GraphicDriver_1.cxx
index 9189043108..fb963ab952 100755
--- a/src/OpenGl/OpenGl_GraphicDriver_1.cxx
+++ b/src/OpenGl/OpenGl_GraphicDriver_1.cxx
@@ -69,7 +69,10 @@ Standard_Boolean OpenGl_GraphicDriver::Begin (const Aspect_Display ADisplay)
 
 void OpenGl_GraphicDriver::End ()
 {
-  openglDisplay.Nullify();
+  // This is unsafe to realease global object here
+  // because noone guaranteed that only one instance of OpenGl_GraphicDriver is used!
+  // So we disable this destructor here until openglDisplay not moved to  OpenGl_GraphicDriver class definition.
+  ///openglDisplay.Nullify();
 }
 
 //=======================================================================
diff --git a/src/OpenGl/OpenGl_telem_view.cxx b/src/OpenGl/OpenGl_telem_view.cxx
index e5075f5589..c751245f82 100644
--- a/src/OpenGl/OpenGl_telem_view.cxx
+++ b/src/OpenGl/OpenGl_telem_view.cxx
@@ -85,7 +85,7 @@ EvalViewMappingMatrix( tel_view_mapping mapping /* View Mapping */,
   }
 
   /* prp between front and back planes */
-  if (!openglDisplay.IsNull() || !openglDisplay->Walkthrough())
+  if (openglDisplay.IsNull() || !openglDisplay->Walkthrough())
   {
     if( mapping->prp[2] < mapping->fpd &&
       mapping->prp[2] > mapping->bpd )