diff --git a/lib/filterx/object-datetime.c b/lib/filterx/object-datetime.c
index 8770c5aa8..48571e4bd 100644
--- a/lib/filterx/object-datetime.c
+++ b/lib/filterx/object-datetime.c
@@ -185,6 +185,7 @@ filterx_typecast_datetime_isodate(FilterXExpr *s, FilterXObject *args[], gsize a
     }
 
   convert_wall_clock_time_to_unix_time(&wct, &ut);
+  ut.ut_gmtoff = 0;
   return filterx_datetime_new(&ut);
 }
 
@@ -288,6 +289,7 @@ _strptime_eval(FilterXExpr *s)
   if (end)
     {
       convert_wall_clock_time_to_unix_time(&wct, &ut);
+      ut.ut_gmtoff = 0;
       result = filterx_datetime_new(&ut);
     }
   else
diff --git a/lib/filterx/tests/test_object_datetime.c b/lib/filterx/tests/test_object_datetime.c
index 2469b6380..9ada66b76 100644
--- a/lib/filterx/tests/test_object_datetime.c
+++ b/lib/filterx/tests/test_object_datetime.c
@@ -196,9 +196,9 @@ Test(filterx_datetime, test_filterx_datetime_repr)
   GString *repr = scratch_buffers_alloc();
   g_string_assign(repr, "foo");
   cr_assert(filterx_object_repr(obj, repr));
-  cr_assert_str_eq("2024-03-18T12:34:13.000+09:00", repr->str);
+  cr_assert_str_eq("2024-03-18T03:34:13.000+00:00", repr->str);
   cr_assert(filterx_object_repr_append(obj, repr));
-  cr_assert_str_eq("2024-03-18T12:34:13.000+09:002024-03-18T12:34:13.000+09:00", repr->str);
+  cr_assert_str_eq("2024-03-18T03:34:13.000+00:002024-03-18T03:34:13.000+00:00", repr->str);
 
   filterx_simple_function_free_args(args, G_N_ELEMENTS(args));
   filterx_object_unref(obj);
@@ -310,7 +310,7 @@ Test(filterx_datetime, test_filterx_datetime_strptime_matching_nth_timefmt)
 
   GString *repr = scratch_buffers_alloc();
   cr_assert(filterx_object_repr(obj, repr));
-  cr_assert_str_eq(repr->str, "2024-04-08T10:11:12.000+01:00");
+  cr_assert_str_eq(repr->str, "2024-04-08T09:11:12.000+00:00");
 
   filterx_object_unref(obj);
   filterx_expr_unref(func_expr);
diff --git a/tests/light/functional_tests/filterx/test_filterx.py b/tests/light/functional_tests/filterx/test_filterx.py
index c3bbfa8d4..cb24d7bfa 100644
--- a/tests/light/functional_tests/filterx/test_filterx.py
+++ b/tests/light/functional_tests/filterx/test_filterx.py
@@ -138,7 +138,7 @@ def test_otel_logrecord_datetime_setter_getter(config, syslog_ng):
 
     assert file_true.get_stats()["processed"] == 1
     assert "processed" not in file_false.get_stats()
-    assert file_true.read_log() == "1701353998.123000+00:00\n"
+    assert file_true.read_log() == "1701346798.123000+00:00\n"
 
 
 def test_otel_logrecord_body_string_setter_getter(config, syslog_ng):
@@ -210,7 +210,7 @@ def test_otel_logrecord_body_datetime_setter_getter(config, syslog_ng):
     # does not distinguish int_value and datetime.
     assert file_true.get_stats()["processed"] == 1
     assert "processed" not in file_false.get_stats()
-    assert file_true.read_log() == "1701353998123000\n"
+    assert file_true.read_log() == "1701346798123000\n"
 
 
 def test_otel_logrecord_body_bytes_setter_getter(config, syslog_ng):
@@ -1211,7 +1211,7 @@ def test_strptime_success_result(config, syslog_ng):
 def test_strftime_success_result(config, syslog_ng):
     (file_true, file_false) = create_config(
         config, """
-        datetime = strptime("2000-01-01T00:00:00 +0200", "%Y-%m-%dT%H:%M:%S %z");
+        datetime = strptime("2000-01-01T02:00:00 +0200", "%Y-%m-%dT%H:%M:%S %z");
         $MSG = strftime("%Y-%m-%dT%H:%M:%S %z", datetime);
         """,
     )
@@ -1219,7 +1219,7 @@ def test_strftime_success_result(config, syslog_ng):
 
     assert file_true.get_stats()["processed"] == 1
     assert "processed" not in file_false.get_stats()
-    assert file_true.read_log() == "2000-01-01T00:00:00 +0200\n"
+    assert file_true.read_log() == "2000-01-01T00:00:00 +0000\n"
 
 
 def test_strptime_guess_missing_year(config, syslog_ng):