diff --git a/tools/python/xen/util/xsm/dummy/dummy.py b/tools/python/xen/util/xsm/dummy/dummy.py
index 04966e4daf..42a41b36c9 100644
--- a/tools/python/xen/util/xsm/dummy/dummy.py
+++ b/tools/python/xen/util/xsm/dummy/dummy.py
@@ -6,6 +6,7 @@ class XSMError(Exception):
     def __str__(self):
         return repr(self.value)
 
+security_dir_prefix = "";
 policy_dir_prefix = "";
 active_policy = "";
 NULL_SSIDREF = 0;