diff --git a/bin/tools/misc.py b/bin/tools/misc.py
index 116a32b106b..9314d8e8055 100644
--- a/bin/tools/misc.py
+++ b/bin/tools/misc.py
@@ -631,6 +631,8 @@ def ustr(value):
 
     if (value is None) or (value is False):
         return value
+    if not value:
+        return u''
     if isinstance(value, unicode):
         return value