diff --git a/qdrant_client/local/order_by.py b/qdrant_client/local/order_by.py
index c695bae85..5b7272cfb 100644
--- a/qdrant_client/local/order_by.py
+++ b/qdrant_client/local/order_by.py
@@ -1,4 +1,4 @@
-from datetime import datetime
+from datetime import datetime, timezone
 
 from qdrant_client.http.models import OrderValue
 from qdrant_client.local.datetime_utils import parse
@@ -7,6 +7,12 @@
 
 
 def datetime_to_microseconds(dt: datetime) -> int:
+    if dt.tzinfo is None:
+        # Assume UTC if no timezone is provided, matching `datetime_utils.parse`
+        # and qdrant core. `datetime.timestamp()` would otherwise read a naive
+        # datetime as local time, making order values depend on where the
+        # client runs.
+        dt = dt.replace(tzinfo=timezone.utc)
     return int(dt.timestamp() * MICROS_PER_SECOND)
 
 
diff --git a/tests/test_order_by.py b/tests/test_order_by.py
new file mode 100644
index 000000000..6bb7f7682
--- /dev/null
+++ b/tests/test_order_by.py
@@ -0,0 +1,58 @@
+import os
+import time
+from datetime import datetime, timedelta, timezone
+
+import pytest
+
+from qdrant_client.local.order_by import to_order_value
+
+# 2024-06-15 12:30:45 UTC
+WALL_CLOCK = (2024, 6, 15, 12, 30, 45)
+EXPECTED_MICROS = 1718454645000000
+
+
+def test_naive_datetime_object_is_interpreted_as_utc() -> None:
+    """A datetime with no tzinfo means UTC, matching how qdrant core reads a
+    datetime string with no offset."""
+    assert to_order_value(datetime(*WALL_CLOCK)) == EXPECTED_MICROS
+
+
+def test_naive_object_string_and_aware_utc_agree() -> None:
+    """The same wall-clock time must order identically however it is spelled."""
+    naive_object = to_order_value(datetime(*WALL_CLOCK))
+    naive_string = to_order_value("2024-06-15 12:30:45")
+    aware_utc = to_order_value(datetime(*WALL_CLOCK, tzinfo=timezone.utc))
+
+    assert naive_object == naive_string == aware_utc
+
+
+def test_aware_non_utc_datetime_is_converted_not_stripped() -> None:
+    """An explicit offset is still honoured -- naive-means-UTC must not turn
+    into treating every datetime as UTC."""
+    aware = datetime(*WALL_CLOCK, tzinfo=timezone(timedelta(hours=5, minutes=30)))
+
+    assert to_order_value(aware) == EXPECTED_MICROS - int(5.5 * 3600 * 1_000_000)
+
+
+@pytest.mark.skipif(
+    not hasattr(time, "tzset"),
+    reason="process timezone is not settable on this platform",
+)
+def test_order_value_does_not_depend_on_the_client_timezone() -> None:
+    """Without this, the naive-object path went through datetime.timestamp(),
+    which reads the machine's local time, so the same call produced different
+    order values on differently-configured clients."""
+    original = os.environ.get("TZ")
+    try:
+        values = []
+        for zone in ("UTC", "Asia/Kolkata", "America/Los_Angeles"):
+            os.environ["TZ"] = zone
+            time.tzset()
+            values.append(to_order_value(datetime(*WALL_CLOCK)))
+        assert values == [EXPECTED_MICROS] * 3
+    finally:
+        if original is None:
+            os.environ.pop("TZ", None)
+        else:
+            os.environ["TZ"] = original
+        time.tzset()