diff --git a/expert/field.py b/expert/field.py
index e60d635..045d724 100644
--- a/expert/field.py
+++ b/expert/field.py
@@ -263,6 +263,7 @@ class SubReportField(Field):
     template = None
     renderer = 'subreport'
     reportFactory = SubReport
+    dbtype = 'subreport'
 
     def getReportInstance(self, row):
         baseReport = row.parent.context