diff --git a/RELEASE.md b/RELEASE.md
index 6ec1e81..c4e3618 100644
--- a/RELEASE.md
+++ b/RELEASE.md
@@ -2,6 +2,10 @@
 
 All major changes in each released version of the archfx-cloud plugin are listed here.
 
+## 0.13.0
+
+- Removed unneed pytz dependency
+
 ## 0.12.0
 
 - Support `ArchFXFlexibleDictionaryReport` direct upload
diff --git a/archfx_cloud/reports/flexible_dictionary.py b/archfx_cloud/reports/flexible_dictionary.py
index e5a1d33..9e8dd25 100644
--- a/archfx_cloud/reports/flexible_dictionary.py
+++ b/archfx_cloud/reports/flexible_dictionary.py
@@ -3,7 +3,6 @@
 import datetime
 from io import BytesIO
 from typing import List, Union
-import pytz
 import msgpack
 from ..utils.slugs import ArchFxDeviceSlug
 from .exceptions import DataError
@@ -135,7 +134,7 @@ def _encode_datetime(obj):
     """Pack a datetime into an isoformat string."""
     if isinstance(obj, datetime.datetime):
         if obj.tzinfo:
-            obj = obj.astimezone(pytz.timezone('UTC'))
+            obj = obj.astimezone(datetime.timezone.utc)
         dt_str = obj.isoformat()
         if dt_str[-6] in ['-', '+']:
             return dt_str
diff --git a/setup.py b/setup.py
index 65e112b..e5e7875 100644
--- a/setup.py
+++ b/setup.py
@@ -24,7 +24,6 @@
     install_requires=[
         'requests>=2.21.0',
         'python-dateutil',
-        'pytz',
         'msgpack>=1.0.2,<1.1',
         'typedargs>=1.1.2,<2',
     ],
diff --git a/tests/test_flexible_report.py b/tests/test_flexible_report.py
index d8acaac..270c5a3 100644
--- a/tests/test_flexible_report.py
+++ b/tests/test_flexible_report.py
@@ -1,7 +1,6 @@
 from datetime import datetime, timezone
 import unittest
 
-import dateutil.parser
 import msgpack
 import requests_mock
 
@@ -90,7 +89,7 @@ def test_report_usage(self):
         events = []
 
         reading = ArchFXDataPoint(
-            timestamp=dateutil.parser.parse('2021-01-20T00:00:00.100000Z'),
+            timestamp=datetime(2021, 1, 20, 0, 0, 0, 100000, timezone.utc),
             stream='0001-5030',
             value=2.0,
             summary_data={'foo': 5, 'bar': 'foobar'},
@@ -99,7 +98,7 @@ def test_report_usage(self):
         )
         events.append(reading)
         reading = ArchFXDataPoint(
-            timestamp=dateutil.parser.parse('2021-01-20T00:00:00.200000+00:00'),
+            timestamp=datetime(2021, 1, 20, 0, 0, 0, 200000, timezone.utc),
             stream=0x15030,
             value=3.0,
             summary_data={'foo': 6, 'bar': 'foobar'},
@@ -107,14 +106,14 @@ def test_report_usage(self):
         )
         events.append(reading)
         reading = ArchFXDataPoint(
-            timestamp=dateutil.parser.parse('2021-01-20T00:00:00.200000+00:00'),
+            timestamp=datetime(2021, 1, 20, 0, 0, 0, 200000, timezone.utc),
             stream='5051',
             value=1.0,
             reading_id=1002
         )
         events.append(reading)
 
-        sent_time = dateutil.parser.parse('2021-01-20T00:00:00.300000Z')
+        sent_time = datetime(2021, 1, 20, 0, 0, 0, 300000, timezone.utc)
         report = ArchFXFlexibleDictionaryReport.FromReadings(
             device='d--1234',
             data=events,
diff --git a/version.py b/version.py
index 727f82d..af87af8 100644
--- a/version.py
+++ b/version.py
@@ -1 +1 @@
-version = '0.12.0'
+version = '0.13.0'