diff --git a/CHANGES.md b/CHANGES.md
index 83f7a7fc..a80d17c0 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,6 @@
 ### 3.29.0 (2023-xx-xx xx:xx:00 UTC)
 
+* Update Msgpack 1.0.4 (b5acfd5) to 1.0.5 (0516c2c)
 * Update SimpleJSON 3.18.1 (c891b95) to 3.19.1 (aeb63ee)
 * Update Tornado Web Server 6.3.0 (7186b86) to 6.3.1 (419838b)
 
diff --git a/lib/msgpack/__init__.py b/lib/msgpack/__init__.py
index 50710218..1300b866 100644
--- a/lib/msgpack/__init__.py
+++ b/lib/msgpack/__init__.py
@@ -6,8 +6,8 @@ import os
 import sys
 
 
-version = (1, 0, 4)
-__version__ = "1.0.4"
+version = (1, 0, 5)
+__version__ = "1.0.5"
 
 
 if os.environ.get("MSGPACK_PUREPYTHON") or sys.version_info[0] == 2:
diff --git a/lib/msgpack/ext.py b/lib/msgpack/ext.py
index 25544c55..23e0d6b4 100644
--- a/lib/msgpack/ext.py
+++ b/lib/msgpack/ext.py
@@ -56,7 +56,7 @@ class Timestamp(object):
         Note: Negative times (before the UNIX epoch) are represented as negative seconds + positive ns.
         """
         if not isinstance(seconds, int_types):
-            raise TypeError("seconds must be an interger")
+            raise TypeError("seconds must be an integer")
         if not isinstance(nanoseconds, int_types):
             raise TypeError("nanoseconds must be an integer")
         if not (0 <= nanoseconds < 10**9):
diff --git a/lib/msgpack/fallback.py b/lib/msgpack/fallback.py
index f560c7b5..e8cebc1b 100644
--- a/lib/msgpack/fallback.py
+++ b/lib/msgpack/fallback.py
@@ -814,7 +814,7 @@ class Packer(object):
                 self._pack_raw_header(n)
                 return self._buffer.write(obj)
             if check(obj, memoryview):
-                n = len(obj) * obj.itemsize
+                n = obj.nbytes
                 if n >= 2**32:
                     raise ValueError("Memoryview is too large")
                 self._pack_bin_header(n)