diff --git a/src/borg/helpers/time.py b/src/borg/helpers/time.py
index 7dfe0d38c4..b98d7fe1f4 100644
--- a/src/borg/helpers/time.py
+++ b/src/borg/helpers/time.py
@@ -26,12 +26,21 @@ def parse_local_timestamp(timestamp, tzinfo=None):
     return dt
 
 
+_EPOCH = datetime(1970, 1, 1, tzinfo=timezone.utc)
+
+
+def utcfromtimestampns(ts_ns: int) -> datetime:
+    # similar to datetime.fromtimestamp, but works with ns and avoids floating point.
+    # also, it would avoid an overflow on 32bit platforms with old glibc.
+    return _EPOCH + timedelta(microseconds=ts_ns // 1000)
+
+
 def timestamp(s):
     """Convert a --timestamp=s argument to a datetime object."""
     try:
         # is it pointing to a file / directory?
-        ts = safe_s(os.stat(s).st_mtime)
-        return datetime.fromtimestamp(ts, tz=timezone.utc)
+        ts_ns = safe_ns(os.stat(s).st_mtime_ns)
+        return utcfromtimestampns(ts_ns)
     except OSError:
         # didn't work, try parsing as an ISO timestamp. if no TZ is given, we assume local timezone.
         return parse_local_timestamp(s)
@@ -44,7 +53,7 @@ def timestamp(s):
 # As long as people are using borg on 32bit platforms to access borg archives, we must
 # keep this value True. But we can expect that we can stop supporting 32bit platforms
 # well before coming close to the year 2038, so this will never be a practical problem.
-SUPPORT_32BIT_PLATFORMS = True  # set this to False before y2038.
+SUPPORT_32BIT_PLATFORMS = False  # set this to False before y2038.
 
 if SUPPORT_32BIT_PLATFORMS:
     # second timestamps will fit into a signed int32 (platform time_t limit).
@@ -84,7 +93,7 @@ def safe_ns(ts):
 
 def safe_timestamp(item_timestamp_ns):
     t_ns = safe_ns(item_timestamp_ns)
-    return datetime.fromtimestamp(t_ns / 1e9, timezone.utc)  # return tz-aware utc datetime obj
+    return utcfromtimestampns(t_ns)  # return tz-aware utc datetime obj
 
 
 def format_time(ts: datetime, format_spec=""):
diff --git a/src/borg/testsuite/archiver/create_cmd_test.py b/src/borg/testsuite/archiver/create_cmd_test.py
index 00edc0935d..f99b187a6f 100644
--- a/src/borg/testsuite/archiver/create_cmd_test.py
+++ b/src/borg/testsuite/archiver/create_cmd_test.py
@@ -223,7 +223,7 @@ def test_nobirthtime(archivers, request):
     assert same_ts_ns(sti.st_birthtime * 1e9, birthtime * 1e9)
     assert same_ts_ns(sto.st_birthtime * 1e9, mtime * 1e9)
     assert same_ts_ns(sti.st_mtime_ns, sto.st_mtime_ns)
-    assert same_ts_ns(sto.st_mtime_ns, mtime * 1e9)
+    assert same_ts_ns(sto.st_mtime_ns, mtime * 10**9)
 
 
 def test_create_stdin(archivers, request):
diff --git a/src/borg/testsuite/archiver/extract_cmd_test.py b/src/borg/testsuite/archiver/extract_cmd_test.py
index fe41c23a00..2b89db1cbc 100644
--- a/src/borg/testsuite/archiver/extract_cmd_test.py
+++ b/src/borg/testsuite/archiver/extract_cmd_test.py
@@ -153,13 +153,13 @@ def has_noatime(some_file):
     sti = os.stat("input/file1")
     sto = os.stat("output/input/file1")
     assert same_ts_ns(sti.st_mtime_ns, sto.st_mtime_ns)
-    assert same_ts_ns(sto.st_mtime_ns, mtime * 1e9)
+    assert same_ts_ns(sto.st_mtime_ns, mtime * 10**9)
     if have_noatime:
         assert same_ts_ns(sti.st_atime_ns, sto.st_atime_ns)
-        assert same_ts_ns(sto.st_atime_ns, atime * 1e9)
+        assert same_ts_ns(sto.st_atime_ns, atime * 10**9)
     else:
         # it touched the input file's atime while backing it up
-        assert same_ts_ns(sto.st_atime_ns, atime * 1e9)
+        assert same_ts_ns(sto.st_atime_ns, atime * 10**9)
 
 
 @pytest.mark.skipif(not is_utime_fully_supported(), reason="cannot setup and execute test without utime")
@@ -179,7 +179,7 @@ def test_birthtime(archivers, request):
     assert same_ts_ns(sti.st_birthtime * 1e9, sto.st_birthtime * 1e9)
     assert same_ts_ns(sto.st_birthtime * 1e9, birthtime * 1e9)
     assert same_ts_ns(sti.st_mtime_ns, sto.st_mtime_ns)
-    assert same_ts_ns(sto.st_mtime_ns, mtime * 1e9)
+    assert same_ts_ns(sto.st_mtime_ns, mtime * 10**9)
 
 
 @pytest.mark.skipif(is_win32, reason="frequent test failures on github CI on win32")
@@ -825,3 +825,19 @@ def test_extract_existing_directory(archivers, request):
         cmd(archiver, "extract", "test")
         st2 = os.stat("input/dir")
     assert st1.st_ino == st2.st_ino
+
+
+@pytest.mark.skipif(not is_utime_fully_supported(), reason="cannot properly setup and execute test without utime")
+def test_extract_y2261(archivers, request):
+    # test if roundtripping of timestamps well beyond y2038 works
+    archiver = request.getfixturevalue(archivers)
+    create_regular_file(archiver.input_path, "file_y2261", contents=b"post y2038 test")
+    # 2261-01-01 00:00:00 UTC as a Unix timestamp (seconds).
+    time_y2261 = 9183110400
+    os.utime("input/file_y2261", (time_y2261, time_y2261))
+    cmd(archiver, "repo-create", RK_ENCRYPTION)
+    cmd(archiver, "create", "test", "input")
+    with changedir("output"):
+        cmd(archiver, "extract", "test")
+    sto = os.stat("output/input/file_y2261")
+    assert same_ts_ns(sto.st_mtime_ns, time_y2261 * 10**9)
diff --git a/src/borg/testsuite/archiver/repo12.tar.gz b/src/borg/testsuite/archiver/repo12.tar.gz
index cd4a45b3f1..72d97b02f7 100644
Binary files a/src/borg/testsuite/archiver/repo12.tar.gz and b/src/borg/testsuite/archiver/repo12.tar.gz differ