diff --git a/src/caoscrawler/crawl.py b/src/caoscrawler/crawl.py
index 79fd72b0b54d132b2ea35b7047448c03fbfc390f..f31d66a95b948967de283e3343640447db93dd7f 100644
--- a/src/caoscrawler/crawl.py
+++ b/src/caoscrawler/crawl.py
@@ -936,7 +936,7 @@ class Crawler(object):
                 if isinstance(el, str):
                     try:
                         # the get_entity function will raise an error if not unique
-                        propval.append(Crawler._get_property_id_for_datatype(rtname=prop.datatype,
+                        propval.append(Crawler._get_property_id_for_datatype(rtname=dt,
                                                                              name=el))
                     except (db.EmptyUniqueQueryError, db.QueryNotUniqueError):
                         logger.error(