diff --git a/plugins/XmlMaterialProfile/XmlMaterialProfile.py b/plugins/XmlMaterialProfile/XmlMaterialProfile.py
index 093638d594..3812c5255c 100644
--- a/plugins/XmlMaterialProfile/XmlMaterialProfile.py
+++ b/plugins/XmlMaterialProfile/XmlMaterialProfile.py
@@ -720,6 +720,8 @@ class XmlMaterialProfile(InstanceContainer):
                         new_hotend_material._dirty = False
 
                         if is_new_material:
+                            if ContainerRegistry.getInstance().isReadOnly(self.getId()):
+                                ContainerRegistry.getInstance().setReadOnlyExplicitly(new_hotend_material.getId())
                             containers_to_add.append(new_hotend_material)
 
                     # there is only one ID for a machine. Once we have reached here, it means we have already found