diff --git a/scripts/ci/cmake/ci-ubuntu20.04-clang10-ompi.cmake b/scripts/ci/cmake/ci-ubuntu20.04-clang10-ompi.cmake
index 1f88788266..7466117143 100644
--- a/scripts/ci/cmake/ci-ubuntu20.04-clang10-ompi.cmake
+++ b/scripts/ci/cmake/ci-ubuntu20.04-clang10-ompi.cmake
@@ -1,7 +1,3 @@
-include(ProcessorCount)
-ProcessorCount(NCPUS)
-math(EXPR N2CPUS "${NCPUS}*2")
-
 set(ENV{CC}  clang-10)
 set(ENV{CXX} clang++-10)
 set(ENV{FC}  gfortran-11)
@@ -37,7 +33,6 @@ CMAKE_CXX_FLAGS:STRING=-Wall
 CMAKE_Fortran_FLAGS:STRING=-Wall
 
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe --mca btl_tcp_if_include lo
-MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
 
 set(CTEST_CMAKE_GENERATOR "Ninja")
diff --git a/scripts/ci/cmake/ci-ubuntu20.04-clang6-ompi.cmake b/scripts/ci/cmake/ci-ubuntu20.04-clang6-ompi.cmake
index 33f5b5b991..2118c80405 100644
--- a/scripts/ci/cmake/ci-ubuntu20.04-clang6-ompi.cmake
+++ b/scripts/ci/cmake/ci-ubuntu20.04-clang6-ompi.cmake
@@ -1,7 +1,3 @@
-include(ProcessorCount)
-ProcessorCount(NCPUS)
-math(EXPR N2CPUS "${NCPUS}*2")
-
 set(ENV{CC}  clang-6.0)
 set(ENV{CXX} clang++-6.0)
 set(ENV{FC}  gfortran-11)
@@ -38,7 +34,6 @@ CMAKE_CXX_FLAGS:STRING=-Wall
 CMAKE_Fortran_FLAGS:STRING=-Wall
 
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe --mca btl_tcp_if_include lo
-MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
 
 # We have a dedicated build for this setup without MPI
diff --git a/scripts/ci/cmake/ci-ubuntu20.04-clang6-static-ompi.cmake b/scripts/ci/cmake/ci-ubuntu20.04-clang6-static-ompi.cmake
index 796384eadb..050c5f836c 100644
--- a/scripts/ci/cmake/ci-ubuntu20.04-clang6-static-ompi.cmake
+++ b/scripts/ci/cmake/ci-ubuntu20.04-clang6-static-ompi.cmake
@@ -1,7 +1,3 @@
-include(ProcessorCount)
-ProcessorCount(NCPUS)
-math(EXPR N2CPUS "${NCPUS}*2")
-
 set(ENV{CC}  clang-6.0)
 set(ENV{CXX} clang++-6.0)
 set(ENV{FC}  gfortran-11)
@@ -39,7 +35,6 @@ CMAKE_CXX_FLAGS:STRING=-Wall
 CMAKE_Fortran_FLAGS:STRING=-Wall
 
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe --mca btl_tcp_if_include lo
-MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
 
 set(CTEST_CMAKE_GENERATOR "Ninja")
diff --git a/scripts/ci/cmake/ci-ubuntu20.04-gcc10-ompi.cmake b/scripts/ci/cmake/ci-ubuntu20.04-gcc10-ompi.cmake
index 757f721531..217bcb58ff 100644
--- a/scripts/ci/cmake/ci-ubuntu20.04-gcc10-ompi.cmake
+++ b/scripts/ci/cmake/ci-ubuntu20.04-gcc10-ompi.cmake
@@ -1,7 +1,3 @@
-include(ProcessorCount)
-ProcessorCount(NCPUS)
-math(EXPR N2CPUS "${NCPUS}*2")
-
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
@@ -37,7 +33,6 @@ CMAKE_CXX_FLAGS:STRING=-Wall
 CMAKE_Fortran_FLAGS:STRING=-Wall
 
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe --mca btl_tcp_if_include lo
-MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
 
 # We have a dedicated build for this setup without MPI
diff --git a/scripts/ci/cmake/ci-ubuntu20.04-gcc11-ompi.cmake b/scripts/ci/cmake/ci-ubuntu20.04-gcc11-ompi.cmake
index e6f66d656c..8991121992 100644
--- a/scripts/ci/cmake/ci-ubuntu20.04-gcc11-ompi.cmake
+++ b/scripts/ci/cmake/ci-ubuntu20.04-gcc11-ompi.cmake
@@ -1,7 +1,3 @@
-include(ProcessorCount)
-ProcessorCount(NCPUS)
-math(EXPR N2CPUS "${NCPUS}*2")
-
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
@@ -37,7 +33,6 @@ CMAKE_CXX_FLAGS:STRING=-Wall
 CMAKE_Fortran_FLAGS:STRING=-Wall
 
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe --mca btl_tcp_if_include lo
-MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
 
 set(CTEST_CMAKE_GENERATOR "Ninja")
diff --git a/scripts/ci/cmake/ci-ubuntu20.04-gcc8-ompi.cmake b/scripts/ci/cmake/ci-ubuntu20.04-gcc8-ompi.cmake
index e6f66d656c..8991121992 100644
--- a/scripts/ci/cmake/ci-ubuntu20.04-gcc8-ompi.cmake
+++ b/scripts/ci/cmake/ci-ubuntu20.04-gcc8-ompi.cmake
@@ -1,7 +1,3 @@
-include(ProcessorCount)
-ProcessorCount(NCPUS)
-math(EXPR N2CPUS "${NCPUS}*2")
-
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
@@ -37,7 +33,6 @@ CMAKE_CXX_FLAGS:STRING=-Wall
 CMAKE_Fortran_FLAGS:STRING=-Wall
 
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe --mca btl_tcp_if_include lo
-MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
 
 set(CTEST_CMAKE_GENERATOR "Ninja")
diff --git a/scripts/ci/cmake/ci-ubuntu20.04-gcc8-static-ompi.cmake b/scripts/ci/cmake/ci-ubuntu20.04-gcc8-static-ompi.cmake
index 132f65d79f..4a0f59bdf5 100644
--- a/scripts/ci/cmake/ci-ubuntu20.04-gcc8-static-ompi.cmake
+++ b/scripts/ci/cmake/ci-ubuntu20.04-gcc8-static-ompi.cmake
@@ -1,7 +1,3 @@
-include(ProcessorCount)
-ProcessorCount(NCPUS)
-math(EXPR N2CPUS "${NCPUS}*2")
-
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
@@ -39,7 +35,6 @@ CMAKE_CXX_FLAGS:STRING=-Wall
 CMAKE_Fortran_FLAGS:STRING=-Wall
 
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe --mca btl_tcp_if_include lo
-MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
 
 set(CTEST_CMAKE_GENERATOR "Ninja")
diff --git a/scripts/ci/cmake/ci-ubuntu20.04-gcc9-ompi.cmake b/scripts/ci/cmake/ci-ubuntu20.04-gcc9-ompi.cmake
index e6f66d656c..8991121992 100644
--- a/scripts/ci/cmake/ci-ubuntu20.04-gcc9-ompi.cmake
+++ b/scripts/ci/cmake/ci-ubuntu20.04-gcc9-ompi.cmake
@@ -1,7 +1,3 @@
-include(ProcessorCount)
-ProcessorCount(NCPUS)
-math(EXPR N2CPUS "${NCPUS}*2")
-
 set(ENV{CC}  gcc)
 set(ENV{CXX} g++)
 set(ENV{FC}  gfortran)
@@ -37,7 +33,6 @@ CMAKE_CXX_FLAGS:STRING=-Wall
 CMAKE_Fortran_FLAGS:STRING=-Wall
 
 MPIEXEC_EXTRA_FLAGS:STRING=--allow-run-as-root --oversubscribe --mca btl_tcp_if_include lo
-MPIEXEC_MAX_NUMPROCS:STRING=${N2CPUS}
 ")
 
 set(CTEST_CMAKE_GENERATOR "Ninja")
diff --git a/scripts/ci/gh-actions/run.sh b/scripts/ci/gh-actions/run.sh
index 86d12a4b49..f3a5bfdb99 100755
--- a/scripts/ci/gh-actions/run.sh
+++ b/scripts/ci/gh-actions/run.sh
@@ -89,6 +89,9 @@ fi
 # Make sure staging tests use localhost
 export ADIOS2_IP=127.0.0.1
 
+# We already paralelize with mpi (MGARD uses omp)
+export OMP_NUM_THREADS=1
+
 # Load any additional setup scripts
 if [ -f gha/scripts/ci/setup-run/ci-${GH_YML_JOBNAME}.sh ]
 then