diff --git a/requirements.d/development.lock.txt b/requirements.d/development.lock.txt
index 131097e7..c58cc41e 100644
--- a/requirements.d/development.lock.txt
+++ b/requirements.d/development.lock.txt
@@ -10,4 +10,3 @@ pytest-cov==3.0.0
 pytest-benchmark==3.4.1
 Cython==0.29.30
 twine==3.8.0
-python-dateutil==2.8.2
diff --git a/requirements.d/development.txt b/requirements.d/development.txt
index 9ecaaafb..8b62f2a0 100644
--- a/requirements.d/development.txt
+++ b/requirements.d/development.txt
@@ -10,4 +10,3 @@ pytest-cov
 pytest-benchmark
 Cython!=0.27
 twine
-python-dateutil
diff --git a/src/borg/testsuite/archiver.py b/src/borg/testsuite/archiver.py
index dd8fa48e..272c0410 100644
--- a/src/borg/testsuite/archiver.py
+++ b/src/borg/testsuite/archiver.py
@@ -1,5 +1,4 @@
 import argparse
-import dateutil.tz
 import errno
 import io
 import json
@@ -2304,8 +2303,8 @@ class ArchiverTestCase(ArchiverTestCaseBase):
     # Given a date and time in local tz, create a UTC timestamp string suitable
     # for create --timestamp command line option
     def _to_utc_timestamp(self, year, month, day, hour, minute, second):
-        dtime = datetime(year, month, day, hour, minute, second, 0, dateutil.tz.gettz())
-        return dtime.astimezone(dateutil.tz.UTC).strftime("%Y-%m-%dT%H:%M:%S")
+        dtime = datetime(year, month, day, hour, minute, second, 0).astimezone()  # local time with local timezone
+        return dtime.astimezone(timezone.utc).strftime("%Y-%m-%dT%H:%M:%S")
 
     def _create_archive_ts(self, name, y, m, d, H=0, M=0, S=0):
         self.cmd(
diff --git a/tox.ini b/tox.ini
index 653e160f..861c2432 100644
--- a/tox.ini
+++ b/tox.ini
@@ -36,5 +36,4 @@ deps =
     pytest
     mypy
     pkgconfig
-    types-python-dateutil
 commands = mypy