diff --git a/swh/model/model.py b/swh/model/model.py
--- a/swh/model/model.py
+++ b/swh/model/model.py
@@ -94,8 +94,8 @@
 @attr.s
 class Origin(BaseModel):
     """Represents a software source: a VCS and an URL."""
-    type = attr.ib(type=str)
     url = attr.ib(type=str)
+    type = attr.ib(type=Optional[str], default=None)
 
 
 @attr.s