diff --git a/src/helma/objectmodel/db/Relation.java b/src/helma/objectmodel/db/Relation.java
index e8a3af61..ab216278 100644
--- a/src/helma/objectmodel/db/Relation.java
+++ b/src/helma/objectmodel/db/Relation.java
@@ -1285,6 +1285,10 @@ public final class Relation {
                 map.put(cnst.foreignKey, home.getString(cnst.localProperty()));
             }
         }
+        // add filter as pseudo-constraint
+        if (filter != null) {
+            map.put("__filter__", filter);
+        }
         return map;
     }