diff --git a/site_ansto/instrument/util/write_tree.tcl b/site_ansto/instrument/util/write_tree.tcl
index 0be43dc3..989eb8d4 100644
--- a/site_ansto/instrument/util/write_tree.tcl
+++ b/site_ansto/instrument/util/write_tree.tcl
@@ -1,3 +1,4 @@
+  namespace eval ::utility {}
   proc ::utility::writeNode {tc_root { do_props 0 } { level 0 }} {
     set space [string repeat "  " $level]
     set val [hval $tc_root]