diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 245b765..5e6ed24 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -44,7 +44,7 @@ jobs:
     - name: Optionally install OpenMM
       if: ${{ matrix.openmm == 'true' }}
       run: |
-        micromamba install "openmm >=7.6" -c conda-forge -yq
+        micromamba install "openmm >=7.6" -c conda-forge/label/openmm_rc -c conda-forge -yq
 
     - name: Verify OpenMM is not installed when not expected
       if: ${{ matrix.openmm == 'false' }}
diff --git a/devtools/conda-envs/test_env.yaml b/devtools/conda-envs/test_env.yaml
index 8602cb6..cdc163d 100644
--- a/devtools/conda-envs/test_env.yaml
+++ b/devtools/conda-envs/test_env.yaml
@@ -1,7 +1,6 @@
 name: openff-units-test
 channels:
   - conda-forge
-  - defaults
 dependencies:
   - python
   - pip