diff --git a/swh/model/hypothesis_strategies.py b/swh/model/hypothesis_strategies.py
--- a/swh/model/hypothesis_strategies.py
+++ b/swh/model/hypothesis_strategies.py
@@ -78,7 +78,7 @@
     return builds(
         OriginVisit,
         visit=integers(0, 1000),
-        origin=origins(),
+        origin=urls(),
         status=sampled_from(['ongoing', 'full', 'partial']),
         type=pgsql_text())
 
diff --git a/swh/model/model.py b/swh/model/model.py
--- a/swh/model/model.py
+++ b/swh/model/model.py
@@ -102,7 +102,7 @@
 class OriginVisit(BaseModel):
     """Represents a visit of an origin at a given point in time, by a
     SWH loader."""
-    origin = attr.ib(type=Origin)
+    origin = attr.ib(type=str)
     date = attr.ib(type=datetime.datetime)
     status = attr.ib(
         type=str,
@@ -130,7 +130,6 @@
         d = d.copy()
         date = d.pop('date')
         return cls(
-            origin=Origin.from_dict(d.pop('origin')),
             date=(date
                   if isinstance(date, datetime.datetime)
                   else dateutil.parser.parse(date)),