diff --git a/falcon/request.py b/falcon/request.py
index 54be8c0..bd83227 100644
--- a/falcon/request.py
+++ b/falcon/request.py
@@ -353,7 +353,8 @@ class Request(object):
 
     @property
     def client_accepts_msgpack(self):
-        return self.client_accepts('application/x-msgpack')
+        return (self.client_accepts('application/x-msgpack')
+                or self.client_accepts('application/msgpack'))
 
     @property
     def client_accepts_xml(self):

Request.client_accepts_msgpack only supports 'application/x-msgpack'
The use of the 'x-' prefix is now discouraged for media types. We should update this Request property to also return True for 'application/msgpack', and verify the change with additional tests.
diff --git a/tests/test_req_vars.py b/tests/test_req_vars.py
index 9e88754..c71f02e 100644
--- a/tests/test_req_vars.py
+++ b/tests/test_req_vars.py
@@ -348,6 +348,12 @@ class TestReqVars(testing.TestBase):
         self.assertFalse(req.client_accepts_json)
         self.assertTrue(req.client_accepts_msgpack)
 
+        headers = {'Accept': 'application/msgpack'}
+        req = Request(testing.create_environ(headers=headers))
+        self.assertFalse(req.client_accepts_xml)
+        self.assertFalse(req.client_accepts_json)
+        self.assertTrue(req.client_accepts_msgpack)
+
         headers = {
             'Accept': 'application/json,application/xml,application/x-msgpack'
         }

pip install -e .
parse_log_pytest
requirements.txt
nose coverage ddt pyyaml requests testtools pytest
apt-get update apt-get install -y gcc
3.9
tools/test-requires
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
certifi==2025.1.31
charset-normalizer==3.4.1
coverage==7.8.0
ddt==1.7.2
exceptiongroup==1.2.2
-e git+https://github.com/falconry/falcon.git@37f175f120aaea587c521715ed4815122446a953#egg=falcon
idna==3.10
iniconfig==2.1.0
nose==1.3.7
packaging==24.2
pluggy==1.5.0
pytest==8.3.5
python-mimeparse==2.0.0
PyYAML==6.0.2
requests==2.32.3
six==1.17.0
testtools==2.7.2
tomli==2.2.1
urllib3==2.3.0

name: falcon
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=3.0.16=h5eee18b_0
  - pip=25.0=py39h06a4308_0
  - python=3.9.21=he870216_1
  - readline=8.2=h5eee18b_0
  - setuptools=75.8.0=py39h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - tzdata=2025a=h04d1e81_0
  - wheel=0.45.1=py39h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - certifi==2025.1.31
      - charset-normalizer==3.4.1
      - coverage==7.8.0
      - ddt==1.7.2
      - exceptiongroup==1.2.2
      - idna==3.10
      - iniconfig==2.1.0
      - nose==1.3.7
      - packaging==24.2
      - pluggy==1.5.0
      - pytest==8.3.5
      - python-mimeparse==2.0.0
      - pyyaml==6.0.2
      - requests==2.32.3
      - six==1.17.0
      - testtools==2.7.2
      - tomli==2.2.1
      - urllib3==2.3.0
prefix: /opt/conda/envs/falcon

tests/test_req_vars.py::TestReqVars::test_client_accepts_props
tests/test_req_vars.py::TestReqVars::test_client_accepts
tests/test_req_vars.py::TestReqVars::test_attribute_headers tests/test_req_vars.py::TestReqVars::test_bogus_content_length_nan tests/test_req_vars.py::TestReqVars::test_bogus_content_length_neg tests/test_req_vars.py::TestReqVars::test_client_accepts_bogus tests/test_req_vars.py::TestReqVars::test_client_prefers tests/test_req_vars.py::TestReqVars::test_content_length tests/test_req_vars.py::TestReqVars::test_content_length_method tests/test_req_vars.py::TestReqVars::test_content_type_method tests/test_req_vars.py::TestReqVars::test_date_1___Date____date__ tests/test_req_vars.py::TestReqVars::test_date_2___If_Modified_since____if_modified_since__ tests/test_req_vars.py::TestReqVars::test_date_3___If_Unmodified_since____if_unmodified_since__ tests/test_req_vars.py::TestReqVars::test_date_invalid_1___Date____date__ tests/test_req_vars.py::TestReqVars::test_date_invalid_2___If_Modified_Since____if_modified_since__ tests/test_req_vars.py::TestReqVars::test_date_invalid_3___If_Unmodified_Since____if_unmodified_since__ tests/test_req_vars.py::TestReqVars::test_date_missing_1_date tests/test_req_vars.py::TestReqVars::test_date_missing_2_if_modified_since tests/test_req_vars.py::TestReqVars::test_date_missing_3_if_unmodified_since tests/test_req_vars.py::TestReqVars::test_empty tests/test_req_vars.py::TestReqVars::test_empty_path tests/test_req_vars.py::TestReqVars::test_host tests/test_req_vars.py::TestReqVars::test_method tests/test_req_vars.py::TestReqVars::test_missing_attribute_header tests/test_req_vars.py::TestReqVars::test_missing_qs tests/test_req_vars.py::TestReqVars::test_nonlatin_path tests/test_req_vars.py::TestReqVars::test_range tests/test_req_vars.py::TestReqVars::test_range_invalid tests/test_req_vars.py::TestReqVars::test_range_unit tests/test_req_vars.py::TestReqVars::test_reconstruct_url tests/test_req_vars.py::TestReqVars::test_relative_uri tests/test_req_vars.py::TestReqVars::test_subdomain tests/test_req_vars.py::TestReqVars::test_uri tests/test_req_vars.py::TestReqVars::test_uri_http_1_0 tests/test_req_vars.py::TestReqVars::test_uri_https
falcon/request.py
falcon/request.py