diff --git a/juju/client/gocookies.py b/juju/client/gocookies.py
index 0c33f0be..f86d4298 100644
--- a/juju/client/gocookies.py
+++ b/juju/client/gocookies.py
@@ -6,7 +6,7 @@
 import json
 import time
 
-import pyrfc3339
+from backports.datetime_fromisoformat import datetime_fromisoformat
 
 
 class GoCookieJar(cookiejar.FileCookieJar):
@@ -52,7 +52,7 @@ def go_to_py_cookie(go_cookie):
     """Convert a Go-style JSON-unmarshaled cookie into a Python cookie"""
     expires = None
     if go_cookie.get("Expires") is not None:
-        t = pyrfc3339.parse(go_cookie["Expires"])
+        t = datetime_fromisoformat(go_cookie["Expires"])
         expires = t.timestamp()
     return cookiejar.Cookie(
         version=0,
@@ -101,8 +101,9 @@ def py_to_go_cookie(py_cookie):
     if py_cookie.path_specified:
         go_cookie["Path"] = py_cookie.path
     if py_cookie.expires is not None:
-        unix_time = datetime.datetime.fromtimestamp(py_cookie.expires)
         # Note: fromtimestamp bizarrely produces a time without
         # a time zone, so we need to use accept_naive.
-        go_cookie["Expires"] = pyrfc3339.generate(unix_time, accept_naive=True)
+        go_cookie["Expires"] = datetime.datetime.fromtimestamp(
+            py_cookie.expires
+        ).isoformat()
     return go_cookie
diff --git a/juju/machine.py b/juju/machine.py
index 3fdd4369..11c4ad8a 100644
--- a/juju/machine.py
+++ b/juju/machine.py
@@ -6,7 +6,7 @@
 import logging
 import typing
 
-import pyrfc3339
+from backports.datetime_fromisoformat import datetime_fromisoformat
 
 from juju.utils import block_until, juju_ssh_key_paths
 
@@ -239,7 +239,7 @@ def agent_status(self):
     @property
     def agent_status_since(self):
         """Get the time when the `agent_status` was last updated."""
-        return pyrfc3339.parse(self.safe_data["agent-status"]["since"])
+        return datetime_fromisoformat(self.safe_data["agent-status"]["since"])
 
     @property
     def agent_version(self):
@@ -266,7 +266,7 @@ def status_message(self):
     @property
     def status_since(self):
         """Get the time when the `status` was last updated."""
-        return pyrfc3339.parse(self.safe_data["instance-status"]["since"])
+        return datetime_fromisoformat(self.safe_data["instance-status"]["since"])
 
     @property
     def dns_name(self):
diff --git a/juju/unit.py b/juju/unit.py
index 64e14ac6..9dd4b16a 100644
--- a/juju/unit.py
+++ b/juju/unit.py
@@ -3,7 +3,7 @@
 
 import logging
 
-import pyrfc3339
+from backports.datetime_fromisoformat import datetime_fromisoformat
 
 from juju.errors import JujuAPIError, JujuError
 
@@ -27,7 +27,7 @@ def agent_status(self):
     @property
     def agent_status_since(self):
         """Get the time when the `agent_status` was last updated."""
-        return pyrfc3339.parse(self.safe_data["agent-status"]["since"])
+        return datetime_fromisoformat(self.safe_data["agent-status"]["since"])
 
     @property
     def is_subordinate(self):
@@ -54,7 +54,7 @@ def workload_status(self):
     @property
     def workload_status_since(self):
         """Get the time when the `workload_status` was last updated."""
-        return pyrfc3339.parse(self.safe_data["workload-status"]["since"])
+        return datetime_fromisoformat(self.safe_data["workload-status"]["since"])
 
     @property
     def workload_status_message(self):
diff --git a/juju/user.py b/juju/user.py
index 7ff0fcc3..204d02b1 100644
--- a/juju/user.py
+++ b/juju/user.py
@@ -3,7 +3,7 @@
 
 import logging
 
-import pyrfc3339
+from backports.datetime_fromisoformat import datetime_fromisoformat
 
 from . import errors, tag
 from .client import client
@@ -31,7 +31,7 @@ def display_name(self):
 
     @property
     def last_connection(self):
-        return pyrfc3339.parse(self._user_info.last_connection)
+        return datetime_fromisoformat(self._user_info.last_connection)
 
     @property
     def access(self):
diff --git a/pyproject.toml b/pyproject.toml
index 228552f0..6de962dd 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,7 +23,6 @@ classifiers = [
 ]
 dependencies = [
     "macaroonbakery>=1.1,<2.0",
-    "pyRFC3339>=1.0,<2.0",
     "pyyaml>=5.1.2",
     "websockets>=13.0.1",
     "paramiko>=2.4.0",
@@ -35,6 +34,7 @@ dependencies = [
     "packaging",
     "typing-extensions>=4.5.0",
     'backports.strenum>=1.3.1; python_version < "3.11"',
+    "backports-datetime-fromisoformat>=2.0.2",
 ]
 [project.optional-dependencies]
 dev = [
diff --git a/setup.py b/setup.py
index f9dd7b57..62b72b43 100644
--- a/setup.py
+++ b/setup.py
@@ -21,7 +21,6 @@
     package_data={"juju": ["py.typed"]},
     install_requires=[
         "macaroonbakery>=1.1,<2.0",
-        "pyRFC3339>=1.0,<2.0",
         "pyyaml>=5.1.2",
         "websockets>=13.0.1",
         "paramiko>=2.4.0",
@@ -33,6 +32,7 @@
         "packaging",
         "typing-extensions>=4.5.0",
         'backports.strenum>=1.3.1; python_version < "3.11"',
+        "backports-datetime-fromisoformat>=2.0.2",
     ],
     extras_require={
         "dev": [
diff --git a/tests/unit/test_gocookies.py b/tests/unit/test_gocookies.py
index 7f04f67f..44d1e7f3 100644
--- a/tests/unit/test_gocookies.py
+++ b/tests/unit/test_gocookies.py
@@ -8,13 +8,14 @@
 import unittest
 import urllib.request
 
-import pyrfc3339
+from backports.datetime_fromisoformat import datetime_fromisoformat
 
 from juju.client.gocookies import GoCookieJar
 
 # cookie_content holds the JSON contents of a Go-produced
 # cookie file (reformatted so it's not all on one line but
 # otherwise unchanged).
+
 cookie_content = """
 [
     {
@@ -223,7 +224,7 @@ def test_expiry_time(self):
         ]"""
         jar = self.load_jar(content)
         got_expires = tuple(jar)[0].expires
-        want_expires = int(pyrfc3339.parse("2345-11-15T18:16:08Z").timestamp())
+        want_expires = int(datetime_fromisoformat("2345-11-15T18:16:08Z").timestamp())
         self.assertEqual(got_expires, want_expires)
 
     def load_jar(self, content):