diff --git a/mypy.ini b/mypy.ini
--- a/mypy.ini
+++ b/mypy.ini
@@ -23,6 +23,9 @@
 [mypy-django.*]  # false positive, only used my hypotesis' extras
 ignore_missing_imports = True
 
+[mypy-iso8601.*]
+ignore_missing_imports = True
+
 [mypy-msgpack.*]
 ignore_missing_imports = True
 
diff --git a/requirements-http.txt b/requirements-http.txt
--- a/requirements-http.txt
+++ b/requirements-http.txt
@@ -4,7 +4,7 @@
 arrow
 decorator
 Flask
+iso8601
 msgpack > 0.5
-python-dateutil
 requests
 blinker  # dependency of sentry-sdk[flask]
diff --git a/swh/core/api/serializers.py b/swh/core/api/serializers.py
--- a/swh/core/api/serializers.py
+++ b/swh/core/api/serializers.py
@@ -10,7 +10,7 @@
 from uuid import UUID
 
 import arrow
-import dateutil.parser
+import iso8601
 import msgpack
 
 from typing import Any, Dict, Union, Tuple
@@ -33,7 +33,7 @@
 
 DECODERS = {
     'arrow': arrow.get,
-    'datetime': dateutil.parser.parse,
+    'datetime': lambda d: iso8601.parse_date(d, default_timezone=None),
     'timedelta': lambda d: datetime.timedelta(**d),
     'uuid': UUID,