diff --git a/src/humanize/filesize.py b/src/humanize/filesize.py
index ca4d468..996506e 100644
--- a/src/humanize/filesize.py
+++ b/src/humanize/filesize.py
@@ -3,9 +3,31 @@
 from __future__ import annotations
 
 suffixes = {
-    "decimal": (" kB", " MB", " GB", " TB", " PB", " EB", " ZB", " YB"),
-    "binary": (" KiB", " MiB", " GiB", " TiB", " PiB", " EiB", " ZiB", " YiB"),
-    "gnu": "KMGTPEZY",
+    "decimal": (
+        " kB",
+        " MB",
+        " GB",
+        " TB",
+        " PB",
+        " EB",
+        " ZB",
+        " YB",
+        " RB",
+        " QB",
+    ),
+    "binary": (
+        " KiB",
+        " MiB",
+        " GiB",
+        " TiB",
+        " PiB",
+        " EiB",
+        " ZiB",
+        " YiB",
+        " RiB",
+        " QiB",
+    ),
+    "gnu": "KMGTPEZYRQ",
 }
 
 
@@ -34,7 +56,9 @@ def naturalsize(
         >>> naturalsize(3000, True)
         '2.9 KiB'
         >>> naturalsize(10**28)
-        '10000.0 YB'
+        '10.0 RB'
+        >>> naturalsize(10**34 * 3)
+        '30000.0 QB'
         >>> naturalsize(-4096, True)
         '-4.0 KiB'
 
@@ -65,15 +89,11 @@ def naturalsize(
     if abs_bytes == 1 and not gnu:
         return "%d Byte" % bytes_
 
-    if abs_bytes < base and not gnu:
-        return "%d Bytes" % bytes_
-
-    if abs_bytes < base and gnu:
-        return "%dB" % bytes_
-
-    for i, s in enumerate(suffix):
-        unit = base ** (i + 2)
+    if abs_bytes < base:
+        return ("%dB" if gnu else "%d Bytes") % bytes_
 
+    for i, s in enumerate(suffix, 2):
+        unit = base**i
         if abs_bytes < unit:
             break
 
diff --git a/tests/test_filesize.py b/tests/test_filesize.py
index 0119d58..416cbf1 100644
--- a/tests/test_filesize.py
+++ b/tests/test_filesize.py
@@ -12,25 +12,56 @@
     "test_args, expected",
     [
         ([300], "300 Bytes"),
-        ([3000], "3.0 kB"),
-        ([3000000], "3.0 MB"),
-        ([3000000000], "3.0 GB"),
-        ([3000000000000], "3.0 TB"),
+        ([1000**1 * 31], "31.0 kB"),
+        ([1000**2 * 32], "32.0 MB"),
+        ([1000**3 * 33], "33.0 GB"),
+        ([1000**4 * 34], "34.0 TB"),
+        ([1000**5 * 35], "35.0 PB"),
+        ([1000**6 * 36], "36.0 EB"),
+        ([1000**7 * 37], "37.0 ZB"),
+        ([1000**8 * 38], "38.0 YB"),
+        ([1000**9 * 39], "39.0 RB"),
+        ([1000**10 * 40], "40.0 QB"),
         ([300, True], "300 Bytes"),
-        ([3000, True], "2.9 KiB"),
-        ([3000000, True], "2.9 MiB"),
+        ([1024**1 * 31, True], "31.0 KiB"),
+        ([1024**2 * 32, True], "32.0 MiB"),
+        ([1024**3 * 33, True], "33.0 GiB"),
+        ([1024**4 * 34, True], "34.0 TiB"),
+        ([1024**5 * 35, True], "35.0 PiB"),
+        ([1024**6 * 36, True], "36.0 EiB"),
+        ([1024**7 * 37, True], "37.0 ZiB"),
+        ([1024**8 * 38, True], "38.0 YiB"),
+        ([1024**9 * 39, True], "39.0 RiB"),
+        ([1024**10 * 40, True], "40.0 QiB"),
+        ([1000**1 * 31, True], "30.3 KiB"),
+        ([1000**2 * 32, True], "30.5 MiB"),
+        ([1000**3 * 33, True], "30.7 GiB"),
+        ([1000**4 * 34, True], "30.9 TiB"),
+        ([1000**5 * 35, True], "31.1 PiB"),
+        ([1000**6 * 36, True], "31.2 EiB"),
+        ([1000**7 * 37, True], "31.3 ZiB"),
+        ([1000**8 * 38, True], "31.4 YiB"),
+        ([1000**9 * 39, True], "31.5 RiB"),
+        ([1000**10 * 40, True], "31.6 QiB"),
+        ([1000**1 * 31, False, True], "30.3K"),
+        ([1000**2 * 32, False, True], "30.5M"),
+        ([1000**3 * 33, False, True], "30.7G"),
+        ([1000**4 * 34, False, True], "30.9T"),
+        ([1000**5 * 35, False, True], "31.1P"),
+        ([1000**6 * 36, False, True], "31.2E"),
+        ([1000**7 * 37, False, True], "31.3Z"),
+        ([1000**8 * 38, False, True], "31.4Y"),
+        ([1000**9 * 39, False, True], "31.5R"),
+        ([1000**10 * 40, False, True], "31.6Q"),
         ([300, False, True], "300B"),
         ([3000, False, True], "2.9K"),
         ([3000000, False, True], "2.9M"),
         ([1024, False, True], "1.0K"),
-        ([10**26 * 30, False, True], "2481.5Y"),
-        ([10**26 * 30, True], "2481.5 YiB"),
-        ([10**26 * 30], "3000.0 YB"),
         ([1, False, False], "1 Byte"),
         ([3141592, False, False, "%.2f"], "3.14 MB"),
         ([3000, False, True, "%.3f"], "2.930K"),
         ([3000000000, False, True, "%.0f"], "3G"),
-        ([10**26 * 30, True, False, "%.3f"], "2481.542 YiB"),
+        ([10**26 * 30, True, False, "%.3f"], "2.423 RiB"),
     ],
 )
 def test_naturalsize(test_args: list[int] | list[int | bool], expected: str) -> None: