diff --git a/src/Mod/Part/Gui/ViewProviderExt.cpp b/src/Mod/Part/Gui/ViewProviderExt.cpp
index c3f1ee67e4..301c466817 100644
--- a/src/Mod/Part/Gui/ViewProviderExt.cpp
+++ b/src/Mod/Part/Gui/ViewProviderExt.cpp
@@ -215,6 +215,7 @@ ViewProviderPartExt::~ViewProviderPartExt()
     coords->unref();
     faceset->unref();
     norm->unref();
+    normb->unref();
     lineset->unref();
     nodeset->unref();
 }