diff --git a/.github/workflows/slow-tests.yml b/.github/workflows/slow-tests.yml
index e9bd458ba..4a5df1944 100644
--- a/.github/workflows/slow-tests.yml
+++ b/.github/workflows/slow-tests.yml
@@ -19,7 +19,6 @@ jobs:
       matrix:
         os: ["ubuntu-latest"]
         python-version: ["3.12"]
-        zarr: ["<3"]
 
     steps:
       - name: Checkout source
@@ -43,10 +42,6 @@ jobs:
         run: |
           python -m pip install -e .[test] memray
 
-      - name: Install zarr${{ matrix.zarr }}
-        run: |
-          python -m pip install -U 'zarr${{ matrix.zarr }}'
-
       - name: Run tests
         run: |
           pytest -vs -k slow --runslow
diff --git a/cubed/tests/test_mem_utilization.py b/cubed/tests/test_mem_utilization.py
index f436ad77d..0e05a6765 100644
--- a/cubed/tests/test_mem_utilization.py
+++ b/cubed/tests/test_mem_utilization.py
@@ -365,6 +365,9 @@ def test_mean(tmp_path, spec, executor):
 
 
 @pytest.mark.slow
+@pytest.mark.skip(
+    reason="Fails with Zarr v3, see https://github.com/cubed-dev/cubed/issues/905"
+)
 def test_sum_partial_reduce(tmp_path, spec, executor):
     a = cubed.random.random(
         (40000, 10000), chunks=(5000, 5000), spec=spec