diff --git a/git_config.py b/git_config.py
index 8c2eb6e9..c19f7662 100644
--- a/git_config.py
+++ b/git_config.py
@@ -795,8 +795,8 @@ class SyncAnalysisState:
                 to be logged.
         """
         self._config = config
-        now = datetime.datetime.utcnow()
-        self._Set("main.synctime", now.isoformat(timespec="microseconds") + "Z")
+        now = datetime.datetime.now(datetime.timezone.utc)
+        self._Set("main.synctime", now.isoformat(timespec="microseconds"))
         self._Set("main.version", "1")
         self._Set("sys.argv", sys.argv)
         for key, value in superproject_logging_data.items():
diff --git a/git_trace2_event_log_base.py b/git_trace2_event_log_base.py
index a111668a..d986b240 100644
--- a/git_trace2_event_log_base.py
+++ b/git_trace2_event_log_base.py
@@ -71,7 +71,7 @@ class BaseEventLog(object):
         if env is None:
             env = os.environ
 
-        self.start = datetime.datetime.utcnow()
+        self.start = datetime.datetime.now(datetime.timezone.utc)
 
         # Save both our sid component and the complete sid.
         # We use our sid component (self._sid) as the unique filename prefix and
@@ -126,7 +126,7 @@ class BaseEventLog(object):
             "event": event_name,
             "sid": self._full_sid,
             "thread": threading.current_thread().name,
-            "time": datetime.datetime.utcnow().isoformat() + "Z",
+            "time": datetime.datetime.now(datetime.timezone.utc).isoformat(),
         }
 
     def StartEvent(self):
@@ -147,7 +147,7 @@ class BaseEventLog(object):
         if result is None:
             result = 0
         exit_event["code"] = result
-        time_delta = datetime.datetime.utcnow() - self.start
+        time_delta = datetime.datetime.now(datetime.timezone.utc) - self.start
         exit_event["t_abs"] = time_delta.total_seconds()
         self._log.append(exit_event)
 
diff --git a/repo b/repo
index d2a4df2e..7f24ff1e 100755
--- a/repo
+++ b/repo
@@ -173,7 +173,7 @@ if not REPO_REV:
 BUG_URL = "https://issues.gerritcodereview.com/issues/new?component=1370071"
 
 # increment this whenever we make important changes to this script
-VERSION = (2, 36)
+VERSION = (2, 37)
 
 # increment this if the MAINTAINER_KEYS block is modified
 KEYRING_VERSION = (2, 3)
@@ -838,7 +838,7 @@ def SetGitTrace2ParentSid(env=None):
 
     KEY = "GIT_TRACE2_PARENT_SID"
 
-    now = datetime.datetime.utcnow()
+    now = datetime.datetime.now(datetime.timezone.utc)
     value = "repo-%s-P%08x" % (now.strftime("%Y%m%dT%H%M%SZ"), os.getpid())
 
     # If it's already set, then append ourselves.
diff --git a/tests/test_git_superproject.py b/tests/test_git_superproject.py
index dc46ec65..600b069f 100644
--- a/tests/test_git_superproject.py
+++ b/tests/test_git_superproject.py
@@ -108,7 +108,9 @@ class SuperprojectTestCase(unittest.TestCase):
             self.assertRegex(log_entry["sid"], self.FULL_SID_REGEX)
         else:
             self.assertRegex(log_entry["sid"], self.SELF_SID_REGEX)
-        self.assertRegex(log_entry["time"], r"^\d+-\d+-\d+T\d+:\d+:\d+\.\d+Z$")
+        self.assertRegex(
+            log_entry["time"], r"^\d+-\d+-\d+T\d+:\d+:\d+\.\d+\+00:00$"
+        )
 
     def readLog(self, log_path):
         """Helper function to read log data into a list."""
diff --git a/tests/test_git_trace2_event_log.py b/tests/test_git_trace2_event_log.py
index 9d4f24c3..d8e963dd 100644
--- a/tests/test_git_trace2_event_log.py
+++ b/tests/test_git_trace2_event_log.py
@@ -90,7 +90,9 @@ class EventLogTestCase(unittest.TestCase):
             self.assertRegex(log_entry["sid"], self.FULL_SID_REGEX)
         else:
             self.assertRegex(log_entry["sid"], self.SELF_SID_REGEX)
-        self.assertRegex(log_entry["time"], r"^\d+-\d+-\d+T\d+:\d+:\d+\.\d+Z$")
+        self.assertRegex(
+            log_entry["time"], r"^\d+-\d+-\d+T\d+:\d+:\d+\.\d+\+00:00$"
+        )
 
     def readLog(self, log_path):
         """Helper function to read log data into a list."""