diff --git a/Calorimeter/CaloTTDetDescr/CaloTTDetDescr/ATLAS_CHECK_THREAD_SAFETY b/Calorimeter/CaloTTDetDescr/CaloTTDetDescr/ATLAS_CHECK_THREAD_SAFETY
new file mode 100644
index 0000000000000000000000000000000000000000..0e6ecd138599155c1d2d5a3d0496a6764390ba79
--- /dev/null
+++ b/Calorimeter/CaloTTDetDescr/CaloTTDetDescr/ATLAS_CHECK_THREAD_SAFETY
@@ -0,0 +1 @@
+Calorimeter/CaloTTDetDescr