diff --git a/.ci_support/environment-openmpi.yml b/.ci_support/environment-openmpi.yml
index a1e8bcf7..3d26ba9c 100644
--- a/.ci_support/environment-openmpi.yml
+++ b/.ci_support/environment-openmpi.yml
@@ -3,7 +3,7 @@ channels:
 dependencies:
 - python
 - numpy
-- openmpi
+- openmpi =4.1.6
 - cloudpickle =3.0.0
 - mpi4py =3.1.6
 - tqdm =4.66.4
diff --git a/.github/workflows/notebooks.yml b/.github/workflows/notebooks.yml
index c1132c72..302a14bf 100644
--- a/.github/workflows/notebooks.yml
+++ b/.github/workflows/notebooks.yml
@@ -35,4 +35,4 @@ jobs:
         shell: bash -l {0}
         run: >
           flux start
-          papermill notebooks/examples.ipynb examples-out.ipynb -k "python3"
\ No newline at end of file
+          papermill notebooks/examples.ipynb examples-out.ipynb -k "python3"
diff --git a/.github/workflows/unittest-flux.yml b/.github/workflows/unittest-flux.yml
index 1331f41b..3ce21135 100644
--- a/.github/workflows/unittest-flux.yml
+++ b/.github/workflows/unittest-flux.yml
@@ -46,10 +46,6 @@ jobs:
         pip install versioneer[toml]==0.29
         pip install . --no-deps --no-build-isolation
         coverage run -a --omit="pympipool/_version.py,tests/*" -m unittest discover tests
-      env:
-        OMPI_MCA_plm: 'isolated'
-        OMPI_MCA_rmaps_base_oversubscribe: 'yes'
-        OMPI_MCA_btl_vader_single_copy_mechanism: 'none'
     - name: Test Flux
       shell: bash -l {0}
       timeout-minutes: 5
@@ -57,10 +53,6 @@ jobs:
         flux start
         coverage run -a --omit="pympipool/_version.py,tests/*" -m unittest tests/test_flux_executor.py tests/test_executor_backend_flux.py;
         coverage xml
-      env:
-        OMPI_MCA_plm: 'isolated'
-        OMPI_MCA_rmaps_base_oversubscribe: 'yes'
-        OMPI_MCA_btl_vader_single_copy_mechanism: 'none'
     - name: Coveralls
       if:  matrix.label == 'linux-64-py-3-12-openmpi'
       uses: coverallsapp/github-action@v2
diff --git a/.github/workflows/unittest-openmpi.yml b/.github/workflows/unittest-openmpi.yml
index e36b7966..df058b41 100644
--- a/.github/workflows/unittest-openmpi.yml
+++ b/.github/workflows/unittest-openmpi.yml
@@ -59,7 +59,3 @@ jobs:
         pip install . --no-deps --no-build-isolation
         cd tests
         python -m unittest discover .
-      env:
-        OMPI_MCA_plm: 'isolated'
-        OMPI_MCA_rmaps_base_oversubscribe: 'yes'
-        OMPI_MCA_btl_vader_single_copy_mechanism: 'none'
diff --git a/binder/environment.yml b/binder/environment.yml
index c36df88c..3855433b 100644
--- a/binder/environment.yml
+++ b/binder/environment.yml
@@ -3,7 +3,7 @@ channels:
 dependencies:
 - python
 - numpy
-- openmpi
+- openmpi =4.1.6
 - cloudpickle =3.0.0
 - mpi4py =3.1.6
 - tqdm =4.66.2
diff --git a/binder/kernel.json b/binder/kernel.json
index 16c69cf5..7bdeb704 100644
--- a/binder/kernel.json
+++ b/binder/kernel.json
@@ -13,4 +13,4 @@
  "metadata": {
   "debugger": true
  }
-}
\ No newline at end of file
+}