diff --git a/.github/workflows/spack_cpu_build.yaml b/.github/workflows/spack_cpu_build.yaml
index a342c9e8..89f41b36 100644
--- a/.github/workflows/spack_cpu_build.yaml
+++ b/.github/workflows/spack_cpu_build.yaml
@@ -14,17 +14,14 @@ jobs:
         # Minimal Build(s)
         # Need S3 mirror to have these builds speedup
         spack_spec:
-          # See #39 - ~python~mpi causes issues
-        # - exago@develop~mpi~ipopt~hiop~python~raja
-          # See #44 - +mpi~python should fail if no python in system,
-          #                       but the runner happens to have one...
-          - exago@develop+mpi~ipopt+hiop~python~raja ^openmpi
+          # See #39 - minimal build useful for sanity
+          - exago@develop~mpi~ipopt~hiop~python~raja
+          # See #16 / #44 - +python~mpi catches mpi4py / python config
+          - exago@develop~mpi~ipopt~hiop+python~raja
           # See #18 - +hiop~mpi causes issues
         # - exago@develop~mpi~ipopt+hiop~python+raja
-          # See #16 - +python~mpi causes issues
-        # - exago@develop~mpi~ipopt+hiop+python~raja
           - exago@develop+mpi~ipopt+hiop+python~raja ^openmpi
-          # See #40 - +hiop+raja~ipopt ^hiop~sparse is useful for edge cases
+          # See #40 - +hiop+raja~ipopt ^hiop~sparse is useful for edge cases in xSDK
           - exago@develop+mpi~ipopt+hiop~python+raja ^openmpi ^hiop+raja~sparse 
 
     name: Build ExaGO with Spack
@@ -41,8 +38,10 @@ jobs:
           SPACK_SPEC: ${{ matrix.spack_spec }}
         run: |
           ls && pwd
-          . ./tpl/spack/share/spack/setup-env.sh
+          . /opt/spack/share/spack/setup-env.sh
           spack debug report
+          spack mirror add spack_public_mirror https://binaries.spack.io/develop
+          spack buildcache keys --install --trust
           spack env create -d ./spack-env
           spack env activate ./spack-env
           spack add $SPACK_SPEC target=x86_64
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f3213209..8e32e86c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -406,8 +406,8 @@ else()
   endif()
 endif()
 
-include(ExaGOCheckPython)
 if(EXAGO_ENABLE_PYTHON)
+  include(ExaGOCheckPython)
   # Build pybind11 target manually
   add_subdirectory(tpl/pybind11)
   add_subdirectory(interfaces/python)
diff --git a/interfaces/python/CMakeLists.txt b/interfaces/python/CMakeLists.txt
index 8f410aa8..e0ab774c 100644
--- a/interfaces/python/CMakeLists.txt
+++ b/interfaces/python/CMakeLists.txt
@@ -31,33 +31,19 @@ target_link_libraries(exago PRIVATE ${EXAGO_PY_LIBS})
 # Find mpi4py c headers
 include(ExaGOFindPythonModule)
 
-find_python_module(mpi4py REQUIRED)
-
-# Get the include directories needed
-if(mpi4py_FOUND)
-  execute_process(
-    COMMAND "${Python_EXECUTABLE}" "-c"
-            "import mpi4py as m; print(m.__version__); print(m.get_include());"
-    RESULT_VARIABLE _mpi4py_SEARCH_SUCCESS
-    OUTPUT_VARIABLE _mpi4py_VALUES
-    ERROR_VARIABLE _mpi4py_ERROR_VALUE
-    OUTPUT_STRIP_TRAILING_WHITESPACE
-  )
-
-  # Find pytest c headers
-  find_python_module(pytest REQUIRED)
-
+if(EXAGO_ENABLE_MPI)
+  find_python_module(mpi4py REQUIRED)
   # Get the include directories needed
-  if(pytest_FOUND)
+  if(mpi4py_FOUND)
     execute_process(
-      COMMAND "${Python_EXECUTABLE}" "-c"
-              "import pytest as p; print(p.__version__);"
-      RESULT_VARIABLE _pytest_SEARCH_SUCCESS
-      OUTPUT_VARIABLE _pytest_VALUES
-      ERROR_VARIABLE _pytest_ERROR_VALUE
+      COMMAND
+        "${Python_EXECUTABLE}" "-c"
+        "import mpi4py as m; print(m.__version__); print(m.get_include());"
+      RESULT_VARIABLE _mpi4py_SEARCH_SUCCESS
+      OUTPUT_VARIABLE _mpi4py_VALUES
+      ERROR_VARIABLE _mpi4py_ERROR_VALUE
       OUTPUT_STRIP_TRAILING_WHITESPACE
     )
-
     # Convert the process output into a list
     string(REGEX REPLACE ";" "\\\\;" _mpi4py_VALUES ${_mpi4py_VALUES})
     string(REGEX REPLACE "\n" ";" _mpi4py_VALUES ${_mpi4py_VALUES})
@@ -78,32 +64,47 @@ if(mpi4py_FOUND)
       mpi4py_VERSION_DECIMAL
       "(${mpi4py_VERSION_MAJOR} * 10000) + (${mpi4py_VERSION_MINOR} * 100) + ${mpi4py_VERSION_PATCH}"
     )
-  endif()
-
-  target_include_directories(exago SYSTEM PRIVATE ${mpi4py_INCLUDE_DIRS})
-
-  string(REGEX REPLACE ";" "\\\\;" _pytest_VALUES ${_pytest_VALUES})
-  string(REGEX REPLACE "\n" ";" _pytest_VALUES ${_pytest_VALUES})
-  list(GET _pytest_VALUES 0 pytest_VERSION)
-  list(GET _pytest_VALUES 0 pytest_INCLUDE_DIRS)
-
-  # Make sure all directory separators are '/'
-  string(REGEX REPLACE "\\\\" "/" pytest_INCLUDE_DIRS ${pytest_INCLUDE_DIRS})
-
-  # Get the major and minor version numbers
-  string(REGEX REPLACE "\\." ";" _pytest_VERSION_LIST ${pytest_VERSION})
-  list(GET _pytest_VERSION_LIST 0 pytest_VERSION_MAJOR)
-  list(GET _pytest_VERSION_LIST 1 pytest_VERSION_MINOR)
-  list(GET _pytest_VERSION_LIST 2 pytest_VERSION_PATCH)
-  string(REGEX MATCH "[0-9]*" pytest_VERSION_PATCH ${pytest_VERSION_PATCH})
-  math(
-    EXPR
-    pytest_VERSION_DECIMAL
-    "(${pytest_VERSION_MAJOR} * 10000) + (${pytest_VERSION_MINOR} * 100) + ${pytest_VERSION_PATCH}"
-  )
-endif()
 
-target_include_directories(exago SYSTEM PRIVATE ${pytest_INCLUDE_DIRS})
+    target_include_directories(exago SYSTEM PRIVATE ${mpi4py_INCLUDE_DIRS})
+  endif(mpi4py_FOUND)
+endif(EXAGO_ENABLE_MPI)
+
+if(EXAGO_RUN_TESTS)
+  # Find pytest c headers
+  find_python_module(pytest REQUIRED)
+
+  # Get the include directories needed
+  if(pytest_FOUND)
+    execute_process(
+      COMMAND "${Python_EXECUTABLE}" "-c"
+              "import pytest as p; print(p.__version__);"
+      RESULT_VARIABLE _pytest_SEARCH_SUCCESS
+      OUTPUT_VARIABLE _pytest_VALUES
+      ERROR_VARIABLE _pytest_ERROR_VALUE
+      OUTPUT_STRIP_TRAILING_WHITESPACE
+    )
+    string(REGEX REPLACE ";" "\\\\;" _pytest_VALUES ${_pytest_VALUES})
+    string(REGEX REPLACE "\n" ";" _pytest_VALUES ${_pytest_VALUES})
+    list(GET _pytest_VALUES 0 pytest_VERSION)
+    list(GET _pytest_VALUES 0 pytest_INCLUDE_DIRS)
+
+    # Make sure all directory separators are '/'
+    string(REGEX REPLACE "\\\\" "/" pytest_INCLUDE_DIRS ${pytest_INCLUDE_DIRS})
+
+    # Get the major and minor version numbers
+    string(REGEX REPLACE "\\." ";" _pytest_VERSION_LIST ${pytest_VERSION})
+    list(GET _pytest_VERSION_LIST 0 pytest_VERSION_MAJOR)
+    list(GET _pytest_VERSION_LIST 1 pytest_VERSION_MINOR)
+    list(GET _pytest_VERSION_LIST 2 pytest_VERSION_PATCH)
+    string(REGEX MATCH "[0-9]*" pytest_VERSION_PATCH ${pytest_VERSION_PATCH})
+    math(
+      EXPR
+      pytest_VERSION_DECIMAL
+      "(${pytest_VERSION_MAJOR} * 10000) + (${pytest_VERSION_MINOR} * 100) + ${pytest_VERSION_PATCH}"
+    )
+    target_include_directories(exago SYSTEM PRIVATE ${pytest_INCLUDE_DIRS})
+  endif(pytest_FOUND)
+endif(EXAGO_RUN_TESTS)
 
 # Install Python bindings to same installation path:
 install(TARGETS exago DESTINATION ${EXAGO_PYTHON_SITELIB})
diff --git a/interfaces/python/exago_python.hpp b/interfaces/python/exago_python.hpp
index 2ec153a9..34e4bde1 100644
--- a/interfaces/python/exago_python.hpp
+++ b/interfaces/python/exago_python.hpp
@@ -7,8 +7,11 @@
 #include <pybind11/stl.h>
 #include <pybind11/stl_bind.h>
 
+#ifdef EXAGO_ENABLE_MPI
 #include <mpi.h>
 #include <mpi4py/mpi4py.h>
+#endif
+
 #include <utils.h>
 #include <string.h>