diff --git a/slo_generator/utils.py b/slo_generator/utils.py
index 302524e3..59419e87 100644
--- a/slo_generator/utils.py
+++ b/slo_generator/utils.py
@@ -200,26 +200,23 @@ def get_human_time(timestamp: int, timezone: Optional[str] = None) -> str:
         timezone (optional): Explicit timezone (e.g: "America/Chicago").
 
     Returns:
-        str: Formatted human-readable date in ISO format (UTC), with
-             time zone added.
+        str: Formatted human-readable date in ISO format.
 
     Example:
-        >>> get_human_time(1565092435, timezone='Europe/Paris')
-        >>> 2019-08-06T11:53:55.000000+02:00
-        which corresponds to the UTC time appended the timezone format
-        to help with display and retrieval of the date localized.
+        >>> get_human_time(1702660513.987654, timezone='Europe/Paris')
+        >>> 2023-12-15T18:15:13.987654+01:00
+        which corresponds to the timestamp in ISO format
     """
     if timezone is not None:  # get timezone from arg
         to_zone = tz.gettz(timezone)
     else:  # auto-detect locale
         to_zone = tz.tzlocal()
-    dt_utc = datetime.utcfromtimestamp(timestamp)
-    dt_tz = dt_utc.replace(tzinfo=to_zone)
-    timeformat = "%Y-%m-%dT%H:%M:%S.%f%z"
-    date_str = datetime.strftime(dt_tz, timeformat)
-    core_str = date_str[:-2]
-    tz_str = date_str[-2:]
-    date_str = f"{core_str}:{tz_str}"
+
+    # NB: as we set tz, dt_tz is an "aware" datetime
+    # see: https://docs.python.org/3/library/datetime.html#aware-and-naive-objects
+    dt_tz = datetime.fromtimestamp(timestamp, tz=to_zone)
+    date_str = dt_tz.isoformat()
+
     return date_str
 
 
diff --git a/tests/unit/fixtures/slo_report_v2.json b/tests/unit/fixtures/slo_report_v2.json
index c6db547a..3a7fa22b 100644
--- a/tests/unit/fixtures/slo_report_v2.json
+++ b/tests/unit/fixtures/slo_report_v2.json
@@ -31,7 +31,7 @@
     }
   },
   "sli_measurement": 0.5,
-  "timestamp": 1567762279.287761,
-  "timestamp_human": "2019-09-05 11:55:01.004603 UTC",
+  "timestamp": 1702660513.987654,
+  "timestamp_human": "2023-12-15T18:15:13.987654+01:00",
   "window": 43200
 }
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index 9152944d..0b0ed8ea 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -25,25 +25,43 @@
 class TestUtils(unittest.TestCase):
     def test_get_human_time(self):
         # Timezones
-        tz_1 = "Europe/Paris"
-        tz_2 = "America/Chicago"
+        tz_UTC = "UTC"
+        tz_Paris = "Europe/Paris"
+        tz_Chicago = "America/Chicago"
 
         # Timestamp 1
-        timestamp = 1565092435
-        utc_time = "2019-08-06T11:53:55.000000"
-        human_paris_1 = get_human_time(timestamp, timezone=tz_1)
-        human_chicago_1 = get_human_time(timestamp, timezone=tz_2)
+        timestamp_20230615T16 = 1686845838
+        utc_time_20230615T16 = "2023-06-15T16:17:18+00:00"
+        paris_time_20230615T16 = "2023-06-15T18:17:18+02:00"
+        chicago_time_20230615T16 = "2023-06-15T11:17:18-05:00"
+        human_utc_20230615T16 = get_human_time(timestamp_20230615T16, timezone=tz_UTC)
+        human_paris_20230615T16 = get_human_time(
+            timestamp_20230615T16, timezone=tz_Paris
+        )
+        human_chicago_20230615T16 = get_human_time(
+            timestamp_20230615T16, timezone=tz_Chicago
+        )
 
         # Timestamp 2
-        timestamp_2 = 1565095633.9568892
-        utc_time_2 = "2019-08-06T12:47:13.956889"
-        human_paris_2 = get_human_time(timestamp_2, timezone=tz_1)
-        human_chicago_2 = get_human_time(timestamp_2, timezone=tz_2)
+        timestamp_20231215T16 = 1702660513.987654
+        utc_time_20231215T16 = "2023-12-15T17:15:13.987654+00:00"
+        paris_time_20231215T16 = "2023-12-15T18:15:13.987654+01:00"
+        chicago_time_20231215T16 = "2023-12-15T11:15:13.987654-06:00"
+        human_utc_20231215T16 = get_human_time(timestamp_20231215T16, timezone=tz_UTC)
+        human_paris_20231215T16 = get_human_time(
+            timestamp_20231215T16, timezone=tz_Paris
+        )
+        human_chicago_20231215T16 = get_human_time(
+            timestamp_20231215T16, timezone=tz_Chicago
+        )
+
+        self.assertEqual(utc_time_20230615T16, human_utc_20230615T16)
+        self.assertEqual(paris_time_20230615T16, human_paris_20230615T16)
+        self.assertEqual(chicago_time_20230615T16, human_chicago_20230615T16)
 
-        self.assertEqual(human_paris_1, utc_time + "+02:00")
-        self.assertEqual(human_chicago_1, utc_time + "-05:00")
-        self.assertEqual(human_paris_2, utc_time_2 + "+02:00")
-        self.assertEqual(human_chicago_2, utc_time_2 + "-05:00")
+        self.assertEqual(utc_time_20231215T16, human_utc_20231215T16)
+        self.assertEqual(paris_time_20231215T16, human_paris_20231215T16)
+        self.assertEqual(chicago_time_20231215T16, human_chicago_20231215T16)
 
     def test_get_backend_cls(self):
         res1 = get_backend_cls("CloudMonitoring")