diff --git a/openstack/python-glanceclient/0001-Fix-unit-tests-broken-by-requests-mock-1.12.0.patch b/openstack/python-glanceclient/0001-Fix-unit-tests-broken-by-requests-mock-1.12.0.patch
new file mode 100644
index 000000000..c8e022ea3
--- /dev/null
+++ b/openstack/python-glanceclient/0001-Fix-unit-tests-broken-by-requests-mock-1.12.0.patch
@@ -0,0 +1,45 @@
+From 300b8c8262d8dcdca7a8d753c3fb8a22cae02d40 Mon Sep 17 00:00:00 2001
+From: Takashi Kajinami <kajinamit@oss.nttdata.com>
+Date: Sun, 28 Apr 2024 22:19:24 +0900
+Subject: [PATCH] Fix unit tests broken by requests-mock >= 1.12.0
+
+requests-mock removed the old compatibility code in 1.12.0[1] and now
+usage of a bare dict for response header causes AttributeError.
+
+[1] https://github.com/jamielennox/requests-mock/commit/e3bd0d1a92e40fa9cb1d587c59157020a45de620
+
+Closes-Bug: #2064011
+Change-Id: Iee86fa3eae86102112987b8648ada73d37ac58e8
+---
+ glanceclient/tests/utils.py | 8 +++++++-
+ 1 file changed, 7 insertions(+), 1 deletion(-)
+
+diff --git a/glanceclient/tests/utils.py b/glanceclient/tests/utils.py
+index 730b928..750fb7e 100644
+--- a/glanceclient/tests/utils.py
++++ b/glanceclient/tests/utils.py
+@@ -14,6 +14,7 @@
+ #    under the License.
+ 
+ import copy
++from email.message import EmailMessage
+ import io
+ import json
+ import testtools
+@@ -112,7 +113,12 @@ class FakeResponse(object):
+         self.body = body
+         self.reason = reason
+         self.version = version
+-        self.headers = headers
++        # NOTE(tkajinam): Make the FakeResponse class compatible with
++        # http.client.HTTPResponse
++        # https://docs.python.org/3/library/http.client.html
++        self.headers = EmailMessage()
++        for header_key in headers:
++            self.headers[header_key] = headers[header_key]
+         self.headers['x-openstack-request-id'] = 'req-1234'
+         self.status_code = status_code
+         self.raw = RawRequest(headers, body=body, reason=reason,
+-- 
+2.44.0
+
diff --git a/openstack/python-glanceclient/python-glanceclient.spec.j2 b/openstack/python-glanceclient/python-glanceclient.spec.j2
index a977bb090..4df883b36 100644
--- a/openstack/python-glanceclient/python-glanceclient.spec.j2
+++ b/openstack/python-glanceclient/python-glanceclient.spec.j2
@@ -12,6 +12,8 @@ License:        {{ license('Apache-2.0') }}
 Group:          Development/Languages/Python
 URL:            https://docs.openstack.org/{{ pypi_name }}
 Source0:        {{ source }}
+# https://review.opendev.org/c/openstack/python-glanceclient/+/917275
+Patch1:         0001-Fix-unit-tests-broken-by-requests-mock-1.12.0.patch
 BuildRequires:  openstack-macros
 BuildRequires:  {{ py3('PrettyTable') }}
 BuildRequires:  {{ py3('ddt') }}