diff --git a/src/humanize/filesize.py b/src/humanize/filesize.py
index 13e5edd..c495fed 100644
--- a/src/humanize/filesize.py
+++ b/src/humanize/filesize.py
@@ -4,30 +4,32 @@
 
 from math import log
 
+from humanize.i18n import _gettext as _
+
 suffixes = {
     "decimal": (
-        " kB",
-        " MB",
-        " GB",
-        " TB",
-        " PB",
-        " EB",
-        " ZB",
-        " YB",
-        " RB",
-        " QB",
+        "kB",
+        "MB",
+        "GB",
+        "TB",
+        "PB",
+        "EB",
+        "ZB",
+        "YB",
+        "RB",
+        "QB",
     ),
     "binary": (
-        " KiB",
-        " MiB",
-        " GiB",
-        " TiB",
-        " PiB",
-        " EiB",
-        " ZiB",
-        " YiB",
-        " RiB",
-        " QiB",
+        "KiB",
+        "MiB",
+        "GiB",
+        "TiB",
+        "PiB",
+        "EiB",
+        "ZiB",
+        "YiB",
+        "RiB",
+        "QiB",
     ),
     "gnu": "KMGTPEZYRQ",
 }
@@ -89,11 +91,12 @@ def naturalsize(
     abs_bytes = abs(bytes_)
 
     if abs_bytes == 1 and not gnu:
-        return f"{int(bytes_)} Byte"
+        return _("%d Byte") % int(bytes_)
 
     if abs_bytes < base:
-        return f"{int(bytes_)}B" if gnu else f"{int(bytes_)} Bytes"
+        return f"{int(bytes_)}B" if gnu else _("%d Bytes") % int(bytes_)
 
     exp = int(min(log(abs_bytes, base), len(suffix)))
-    ret: str = format % (bytes_ / (base**exp)) + suffix[exp - 1]
+    space = "" if gnu else " "
+    ret: str = format % (bytes_ / (base**exp)) + space + _(suffix[exp - 1])
     return ret
diff --git a/src/humanize/locale/fr_FR/LC_MESSAGES/humanize.po b/src/humanize/locale/fr_FR/LC_MESSAGES/humanize.po
index 6aae582..e9a4220 100644
--- a/src/humanize/locale/fr_FR/LC_MESSAGES/humanize.po
+++ b/src/humanize/locale/fr_FR/LC_MESSAGES/humanize.po
@@ -363,3 +363,73 @@ msgstr "hier"
 #, python-format
 msgid "%s and %s"
 msgstr "%s et %s"
+
+# --- filesize units (naturalsize) ---
+#, python-format
+msgid "%d Byte"
+msgstr "%d octet"
+
+#, python-format
+msgid "%d Bytes"
+msgstr "%d octets"
+
+msgid "kB"
+msgstr "Ko"
+
+msgid "MB"
+msgstr "Mo"
+
+msgid "GB"
+msgstr "Go"
+
+msgid "TB"
+msgstr "To"
+
+msgid "PB"
+msgstr "Po"
+
+msgid "EB"
+msgstr "Eo"
+
+msgid "ZB"
+msgstr "Zo"
+
+msgid "YB"
+msgstr "Yo"
+
+msgid "RB"
+msgstr "Ro"
+
+msgid "QB"
+msgstr "Qo"
+
+# --- binary filesize units ---
+msgid "KiB"
+msgstr "Kio"
+
+msgid "MiB"
+msgstr "Mio"
+
+msgid "GiB"
+msgstr "Gio"
+
+msgid "TiB"
+msgstr "Tio"
+
+msgid "PiB"
+msgstr "Pio"
+
+msgid "EiB"
+msgstr "Eio"
+
+msgid "ZiB"
+msgstr "Zio"
+
+msgid "YiB"
+msgstr "Yio"
+
+msgid "RiB"
+msgstr "Rio"
+
+msgid "QiB"
+msgstr "Qio"
diff --git a/tests/test_i18n.py b/tests/test_i18n.py
index 59e896c..3a4c2b9 100644
--- a/tests/test_i18n.py
+++ b/tests/test_i18n.py
@@ -157,6 +157,39 @@ def test_intword_i18n(locale: str, number: int, expected_result: str) -> None:
         humanize.i18n.deactivate()
 
 
+@pytest.mark.parametrize(
+    "locale, value, expected_result",
+    [
+        ("fr_FR", 1, "1 octet"),
+        ("fr_FR", 42, "42 octets"),
+        ("fr_FR", 42_000, "42.0 Ko"),
+        ("fr_FR", 42_000_000, "42.0 Mo"),
+        ("fr_FR", 42_000_000_000, "42.0 Go"),
+        ("fr_FR", -42_000, "-42.0 Ko"),
+    ],
+)
+def test_naturalsize_i18n(locale: str, value: float, expected_result: str) -> None:
+    try:
+        humanize.i18n.activate(locale)
+    except FileNotFoundError:
+        pytest.skip("Generate .mo with scripts/generate-translation-binaries.sh")
+    else:
+        assert humanize.naturalsize(value) == expected_result
+    finally:
+        humanize.i18n.deactivate()
+
+
+def test_naturalsize_i18n_binary() -> None:
+    try:
+        humanize.i18n.activate("fr_FR")
+    except FileNotFoundError:
+        pytest.skip("Generate .mo with scripts/generate-translation-binaries.sh")
+    else:
+        assert humanize.naturalsize(3000, binary=True) == "2.9 Kio"
+    finally:
+        humanize.i18n.deactivate()
+
+
 @pytest.mark.parametrize(
     "locale, expected_result",
     [