diff --git a/.github/workflows/branching-tests.yml b/.github/workflows/branching-tests.yml
index 9c190b1..9439055 100644
--- a/.github/workflows/branching-tests.yml
+++ b/.github/workflows/branching-tests.yml
@@ -23,52 +23,63 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
 
     strategy:
       fail-fast: true
 
       matrix:
+        os: [ ubuntu-latest, macos-latest ]
         build_type: [ Release, Debug ]
         cpp_compiler: [ g++, clang++ ]
         mpi: [ ON, OFF ]
 
+        exclude:
+          - os: macos-latest
+            cpp_compiler: g++
+
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
 
       - name: Install dependencies
+        if: matrix.os == 'ubuntu-latest' && matrix.mpi == 'ON'
         run: |
-          sudo apt install -y mpich python3-pybind11 python3-dev
-      
+          sudo apt install -y libopenmpi-dev
 
+      - name: Install dependencies
+        if: matrix.os == 'macos-latest' && matrix.mpi == 'ON'
+        run: |
+          brew install mpich
+      
       - name: Install and Test Python CUI (MPI)
         if: matrix.mpi == 'ON'
         run: |
-          pip install -U pip
-          USE_MPI=1 pip install -U . --verbose
+          pip install -U pip pybind11
+          USE_MPI=1 CXX=${{ matrix.cpp_compiler }} pip install -U . --verbose
           echo -e 'p cnf 2 2\n1 2 0\n-1 -2 0' | mpirun -n 2 pysa-dpll sat
 
       - name: Install and Test Python CUI
         if: matrix.mpi == 'OFF'
         run: |
-          pip install -U pip
-          pip install -U . --verbose
+          pip install -U pip pybind11
+          CXX=${{ matrix.cpp_compiler }} pip install -U . --verbose
           echo -e 'p cnf 2 2\n1 2 0\n-1 -2 0' | pysa-dpll sat
 
       - name: Configure CMake
         run: >
-          cmake -B ${{github.workspace}}/build \
-                -S ${{ github.workspace }} \
-                -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} \
-                -DCMAKE_CXX_COMPILER=${{ matrix.cpp_compiler }} \
-                -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} \
-                -DMPI=${{ matrix.mpi }}
+          CXX=${{ matrix.cpp_compiler }} \
+              cmake -B ${{ github.workspace }}/build \
+                    -S ${{ github.workspace }} \
+                    -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} \
+                    -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} \
+                    -Dpybind11_DIR=$( python -m pybind11 --cmakedir ) \
+                    -DMPI=${{ matrix.mpi }}
 
       - name: Build
-        run: cmake --build ${{github.workspace}}/build 
+        run: cmake --build ${{ github.workspace }}/build 
                    --config ${{ matrix.build_type }}
 
       - name: Test
-        working-directory: ${{github.workspace}}/build/tests
+        working-directory: ${{ github.workspace }}/build/tests
         run: ctest -C ${{ matrix.build_type }} --rerun-failed --output-on-failure
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 50c768a..0735cb2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -31,15 +31,15 @@ add_compile_options(-O3 -Wall -Wpedantic -Wfatal-errors)
 # Use MPI
 option(MPI "Build with MPI" OFF)
 
-# Find MPI package
-find_package(MPI)
-
 # If MPI exists, compile the code using MPI
-if (MPI AND MPI_FOUND)
+if (MPI)
+  find_package(MPI REQUIRED)
   message(STATUS "MPI Enabled")
   add_compile_definitions(USE_MPI)
   include_directories(${MPI_CXX_HEADER_DIR})
   link_libraries(MPI::MPI_CXX)
+else()
+  message(STATUS "MPI Disabled")
 endif ()
 
 # Find pthreads
diff --git a/setup.py b/setup.py
index 37fe58c..054409f 100644
--- a/setup.py
+++ b/setup.py
@@ -76,6 +76,11 @@ def build_extension(self, ext):
         if USE_MPI:
             cmake_args.append('-DMPI=ON')
 
+            # If provided, override MPIEXEC_EXECUTABLE
+            if 'MPIEXEC_EXECUTABLE' in os.environ:
+                cmake_args.append(
+                    f'-DMPIEXEC_EXECUTABLE={os.environ["MPIEXEC_EXECUTABLE"]}')
+
         build_args = ['--config', cfg]
 
         if not os.path.exists(self.build_temp):