diff --git a/.github/workflows/compatibility_tests.yml b/.github/workflows/compatibility_tests.yml
index c9ab85053..48a3e73b8 100644
--- a/.github/workflows/compatibility_tests.yml
+++ b/.github/workflows/compatibility_tests.yml
@@ -34,7 +34,7 @@ jobs:
       fail-fast: false
       matrix:
         # note: The `macos-latest` is latest Catalina version, and not Big Sur. So we explicitly ask for Big Sur (`macos-11`)
-        os: [ubuntu-latest, macos-latest, macos-11]
+        os: [ubuntu-latest, macos-latest, macos-13]
         python-version: ["3.10", "3.11", "3.12"]
         cellxgene_build: [main, latest]
         # add anndata pinned version test for subset of matrix configurations,
diff --git a/server/requirements.txt b/server/requirements.txt
index ddbdb3f3d..7e1d9dedb 100644
--- a/server/requirements.txt
+++ b/server/requirements.txt
@@ -7,7 +7,7 @@ Flask-Cors>=3.0.9
 Flask-RESTful>=0.3.6
 flask-server-timing>=0.1.2
 flask-talisman>=0.7.0
-flatbuffers>=1.11.0,<2.0.0 # cellxgene is not compatible with 2.0.0. Requires migration
+flatbuffers==24.3.25 # cellxgene is not compatible with 2.0.0. Requires migration
 flatten-dict>=0.2.0
 fsspec>0.8.0
 gunicorn>=20.0.4