diff --git a/src/caosadvancedtools/crawler.py b/src/caosadvancedtools/crawler.py
index 699000dc6d3fd4f5dc6052349cf9baa4d43d8eaa..48ff406f8549d1bfca15ca5f1854d927ff196aed 100644
--- a/src/caosadvancedtools/crawler.py
+++ b/src/caosadvancedtools/crawler.py
@@ -37,6 +37,7 @@ match. This occurs in basically three steps:
 
 
 import traceback
+from datetime import datetime
 
 import caosdb as db
 from caosdb.exceptions import TransactionError
@@ -300,5 +301,7 @@ def get_value(prop):
 
     if isinstance(prop.value, db.Entity):
         return prop.value.id
+    elif isinstance(prop.value, datetime):
+        return prop.value.isoformat()
     else:
         return prop.value