diff --git a/src/humanize/filesize.py b/src/humanize/filesize.py
index 063affe0..3ee79e6c 100644
--- a/src/humanize/filesize.py
+++ b/src/humanize/filesize.py
@@ -90,10 +90,12 @@ def naturalsize(
     bytes_ = float(value)
     abs_bytes = abs(bytes_)
 
-    if abs_bytes == 1 and not gnu:
+    if abs_bytes == 1 and not gnu and float(bytes_).is_integer():
         return _("%d Byte") % int(bytes_)
 
     if abs_bytes < base:
+        if not float(bytes_).is_integer():
+            return f"{format % bytes_}B" if gnu else _("%s Bytes") % (format % bytes_)
         return f"{int(bytes_)}B" if gnu else _("%d Bytes") % int(bytes_)
 
     from math import log
diff --git a/tests/test_filesize.py b/tests/test_filesize.py
index 645751b9..44d9aa14 100644
--- a/tests/test_filesize.py
+++ b/tests/test_filesize.py
@@ -74,10 +74,12 @@
         ([3000, False, True, "%.3f"], "2.930K"),
         ([3000000000, False, True, "%.0f"], "3G"),
         ([10**26 * 30, True, False, "%.3f"], "2.423 RiB"),
-        ([1.123456789], "1 Bytes"),
+        ([1.123456789], "1.1 Bytes"),
+        ([1.5], "1.5 Bytes"),
+        ([1.5, False, True], "1.5B"),
         ([1.123456789 * 10**3], "1.1 kB"),
         ([1.123456789 * 10**6], "1.1 MB"),
-        ([1.123456789, False, True], "1B"),
+        ([1.123456789, False, True], "1.1B"),
         ([1.123456789 * 10**3, False, True], "1.1K"),
         ([1.123456789 * 10**6, False, True], "1.1M"),
         # Rounding must not leave the mantissa at the base while a larger suffix