diff --git a/pyatspi/constants.py b/pyatspi/constants.py
index e9a839a86b17ae066dcaf31147b78825c5c5775b..0d81fee1bfe7c51bd6523255cc540b02da7aec15 100644
--- a/pyatspi/constants.py
+++ b/pyatspi/constants.py
@@ -99,6 +99,7 @@ EVENT_TREE = {
     ['object:property-change:accessible-parent', 
     'object:property-change:accessible-name',
     'object:property-change:accessible-description',
+    'object:property-change:accessible-help-text',
     'object:property-change:accessible-value',
     'object:property-change:accessible-role',
     'object:property-change:accessible-table-caption',