diff --git a/CMakeLists.txt b/CMakeLists.txt
index a7bf11bd3..edc559db4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,6 +12,9 @@ message( STATUS
 ============================================================
 ")
 
+message( STATUS "Running with CMake from: ${CMAKE_COMMAND}" )
+message( STATUS "Current source dir (for OpenCoarrays): ${CMAKE_CURRENT_SOURCE_DIR}")
+
 # Add option and check environment to determine if developer tests should be run
 if($ENV{OPENCOARRAYS_DEVELOPER})
   option(CAF_RUN_DEVELOPER_TESTS "Run tests intended only for developers" ON)
@@ -80,8 +83,10 @@ string(REGEX REPLACE "-rc[0-9]+$"
        "${OpenCoarraysVersion}")
 
 project(opencoarrays VERSION "${OPENCOARRAYS_CMAKE_PROJECT_VERSION}" LANGUAGES C Fortran)
+
 message( STATUS "Building OpenCoarrays version: ${full_git_describe}" )
 set(OpenCoarrays_dist_string "OpenCoarrays-${full_git_describe}")
+message( STATUS "Building for target architecture: ${CMAKE_SYSTEM_PROCESSOR}" )
 
 #Print an error message on an attempt to build inside the source directory tree:
 if ("${CMAKE_CURRENT_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_BINARY_DIR}")
@@ -838,7 +843,9 @@ include(cmake/AddInstallationScriptTest.cmake )
 add_installation_script_test(installation-scripts.sh src/tests/installation/)
 
 # Test ISO_Fortran_binding library
-if( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" )
+if( (( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" ) AND ( "${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "x86_64" ))
+    OR ( CAF_RUN_DEVELOPER_TESTS OR $ENV{OPENCOARRAYS_DEVELOPER} ) )
+  # See https://github.com/sourceryinstitute/OpenCoarrays/issues/523#issuecomment-401613209
   add_test(NAME ISO_Fortran_binding_tests COMMAND "${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/ISO_Fortran_binding_tests")
 endif()
 
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 23c23c5f0..3708bc4ee 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,9 +1,4 @@
-set(directories_to_build mpi tests)
-
-if( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" )
-  LIST( APPEND directories_to_build iso-fortran-binding )
-endif()
-
+set(directories_to_build mpi tests iso-fortran-binding)
 foreach(directory ${directories_to_build})
   add_subdirectory(${directory})
 endforeach()
diff --git a/src/mpi/CMakeLists.txt b/src/mpi/CMakeLists.txt
index 488cf2f82..1b0210bbb 100644
--- a/src/mpi/CMakeLists.txt
+++ b/src/mpi/CMakeLists.txt
@@ -21,7 +21,7 @@ if (mpi_version_out MATCHES "[Oo]pen[ -][Mm][Pp][Ii]")
   message( STATUS "OpenMPI detected")
   set ( openmpi true PARENT_SCOPE)
   # Write out a host file because OMPI's mpiexec is dumb
-  file(APPEND ${CMAKE_BINARY_DIR}/hostfile "${HOST_NAME} slots=${N_CPU}\n")
+  file(WRITE ${CMAKE_BINARY_DIR}/hostfile "${HOST_NAME} slots=${N_CPU}\n")
 endif ()
 
 if("${CMAKE_Fortran_COMPILER_ID}" STREQUAL "GNU")
diff --git a/src/tests/unit/CMakeLists.txt b/src/tests/unit/CMakeLists.txt
index 7e7ef68ac..67d6d37e4 100644
--- a/src/tests/unit/CMakeLists.txt
+++ b/src/tests/unit/CMakeLists.txt
@@ -5,7 +5,6 @@ if (${opencoarrays_aware_compiler})
   add_subdirectory(collectives)
   add_subdirectory(sync)
   add_subdirectory(events)
-  add_subdirectory(iso-fortran-binding)
   if (gfortran_compiler)
     if(NOT CMAKE_Fortran_COMPILER_VERSION VERSION_LESS 7)
       add_subdirectory(fail_images)
@@ -17,3 +16,7 @@ if (${opencoarrays_aware_compiler})
 else()
   add_subdirectory(extensions)
 endif()
+if( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR
+    (CAF_RUN_DEVELOPER_TESTS OR $ENV{OPENCOARRAYS_DEVELOPER}))
+  add_subdirectory(iso-fortran-binding)
+endif()