diff --git a/histories/models.py b/histories/models.py
index 401b67d..f825026 100644
--- a/histories/models.py
+++ b/histories/models.py
@@ -174,7 +174,7 @@ def generate_partial_history(user, t_start):
     urls = crawler.output_tree
     for url in urls:
         t_start += 5 * random.weibullvariate(1, 1.5)
-        result.append(PartialHistoryEntry(url, timestamp))
+        result.append(PartialHistoryEntry(url.url, timestamp))
     return result