diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,2 +1,2 @@
 swh.core[db,http] >= 0.0.60
-swh.model >= 0.6.1
+swh.model >= 0.6.6
diff --git a/swh/journal/pytest_plugin.py b/swh/journal/pytest_plugin.py
--- a/swh/journal/pytest_plugin.py
+++ b/swh/journal/pytest_plugin.py
@@ -80,7 +80,7 @@
 
         if object_type in ("content", "skipped_content"):
             for value in received_values:
-                del value["ctime"]
+                value.pop("ctime", None)
         if object_type == "content":
             known_objects = [attr.evolve(o, data=None) for o in known_objects]
 
@@ -96,7 +96,7 @@
         for value in known_objects:
             expected_value = value.to_dict()
             if value.object_type in ("content", "skipped_content"):
-                del expected_value["ctime"]
+                expected_value.pop("ctime", None)
             assert expected_value in received_values, (
                 f"expected {object_type} value {value!r} is "
                 "absent from consumed messages"