diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,2 +1,2 @@
 swh.core[http] >= 0.4
-swh.model >= 3.0.0
+swh.model >= 4.4.0
diff --git a/swh/deposit/utils.py b/swh/deposit/utils.py
--- a/swh/deposit/utils.py
+++ b/swh/deposit/utils.py
@@ -113,7 +113,7 @@
 
     return {
         "timestamp": tstz.timestamp.to_dict(),
-        "offset": tstz.offset,
+        "offset": tstz.offset_minutes(),
     }