diff --git a/swh/scheduler/model.py b/swh/scheduler/model.py
--- a/swh/scheduler/model.py
+++ b/swh/scheduler/model.py
@@ -145,7 +145,7 @@
         type=str, validator=[type_validator()], metadata={"primary_key": True}
     )
     extra_loader_arguments = attr.ib(
-        type=Dict[str, str], validator=[type_validator()], factory=dict
+        type=Dict[str, Any], validator=[type_validator()], factory=dict
     )
 
     last_update = attr.ib(
diff --git a/swh/scheduler/tests/test_model.py b/swh/scheduler/tests/test_model.py
--- a/swh/scheduler/tests/test_model.py
+++ b/swh/scheduler/tests/test_model.py
@@ -106,11 +106,13 @@
         "arguments": {"args": [], "kwargs": {"url": "http://example.com/"}},
     }
 
+    loader_args = {"foo": "bar", "baz": {"foo": "bar"}}
+
     origin_w_args = model.ListedOrigin(
         lister_id=uuid.uuid4(),
         url="http://example.com/svn/",
         visit_type="svn",
-        extra_loader_arguments={"foo": "bar"},
+        extra_loader_arguments=loader_args,
     )
 
     task_w_args = origin_w_args.as_task_dict()
@@ -118,6 +120,6 @@
         "type": "load-svn",
         "arguments": {
             "args": [],
-            "kwargs": {"url": "http://example.com/svn/", "foo": "bar"},
+            "kwargs": {"url": "http://example.com/svn/", **loader_args},
         },
     }