diff --git a/src/borg/archiver/_common.py b/src/borg/archiver/_common.py
index ebba27ae5..0d058e9b0 100644
--- a/src/borg/archiver/_common.py
+++ b/src/borg/archiver/_common.py
@@ -8,7 +8,7 @@ from ..constants import *  # NOQA
 from ..cache import Cache, assert_secure
 from ..helpers import Error
 from ..helpers import SortBySpec, positive_int_validator, location_validator, Location, relative_time_marker_validator
-from ..helpers import Highlander
+from ..helpers import Highlander, octal_int
 from ..helpers.argparsing import SUPPRESS
 from ..helpers.nanorst import rst_to_terminal
 from ..manifest import Manifest, AI_HUMAN_SORT_KEYS
@@ -510,7 +510,7 @@ def define_common_options(add_common_option):
         "--umask",
         metavar="M",
         dest="umask",
-        type=lambda s: s if isinstance(s, int) else int(s, 8),
+        type=octal_int,
         default=UMASK_DEFAULT,
         action=Highlander,
         help="set umask to M (local only, default: %(default)04o)",
diff --git a/src/borg/archiver/create_cmd.py b/src/borg/archiver/create_cmd.py
index b5c3bf2c6..266bcefb7 100644
--- a/src/borg/archiver/create_cmd.py
+++ b/src/borg/archiver/create_cmd.py
@@ -16,7 +16,7 @@ from ..archive import FilesystemObjectProcessors, MetadataCollector, ChunksProce
 from ..cache import Cache
 from ..constants import *  # NOQA
 from ..helpers import comment_validator, ChunkerParams, FilesystemPathSpec, CompressionSpec
-from ..helpers import archivename_validator, FilesCacheMode
+from ..helpers import archivename_validator, FilesCacheMode, octal_int
 from ..helpers import eval_escapes
 from ..helpers import timestamp, archive_ts_now
 from ..helpers import get_cache_dir, os_stat, get_strip_prefix, slashify
@@ -827,7 +827,7 @@ class CreateMixIn:
             "--stdin-mode",
             metavar="M",
             dest="stdin_mode",
-            type=lambda s: s if isinstance(s, int) else int(s, 8),
+            type=octal_int,
             default=STDIN_MODE_DEFAULT,
             action=Highlander,
             help="set mode to M in archive for stdin data (default: %(default)04o)",
diff --git a/src/borg/helpers/__init__.py b/src/borg/helpers/__init__.py
index d9e90f5ce..2e2c30709 100644
--- a/src/borg/helpers/__init__.py
+++ b/src/borg/helpers/__init__.py
@@ -25,7 +25,7 @@ from .fs import O_, flags_dir, flags_special_follow, flags_special, flags_base,
 from .fs import HardLinkManager
 from .misc import sysinfo, log_multi, consume
 from .misc import ChunkIteratorFileWrapper, open_item, chunkit, iter_separated, ErrorIgnoringTextIOWrapper
-from .parseformat import bin_to_hex, hex_to_bin, safe_encode, safe_decode
+from .parseformat import octal_int, bin_to_hex, hex_to_bin, safe_encode, safe_decode
 from .parseformat import text_to_json, binary_to_json, remove_surrogates, join_cmd
 from .parseformat import eval_escapes, decode_dict, positive_int_validator, interval
 from .parseformat import (
diff --git a/src/borg/helpers/parseformat.py b/src/borg/helpers/parseformat.py
index c84326941..f372827e4 100644
--- a/src/borg/helpers/parseformat.py
+++ b/src/borg/helpers/parseformat.py
@@ -35,6 +35,12 @@ if TYPE_CHECKING:
     from ..item import ItemDiff
 
 
+def octal_int(s):
+    if isinstance(s, int):
+        return s
+    return int(s, 8)
+
+
 def bin_to_hex(binary):
     return binascii.hexlify(binary).decode("ascii")