diff --git a/examples/COUPLE/simple/CMakeLists.txt b/examples/COUPLE/simple/CMakeLists.txt
index d9b877ec76..46eedcf2d4 100644
--- a/examples/COUPLE/simple/CMakeLists.txt
+++ b/examples/COUPLE/simple/CMakeLists.txt
@@ -38,7 +38,46 @@ if(NOT LAMMPS_SOURCE_DIR)
 endif()
 
 add_executable(simpleCC simple.cpp)
-target_link_libraries(simpleCC LAMMPS::lammps)
+target_link_libraries(simpleCC PRIVATE LAMMPS::lammps MPI::MPI_CXX)
 
 add_executable(simpleC simple.c)
-target_link_libraries(simpleC LAMMPS::lammps)
+target_link_libraries(simpleC PRIVATE LAMMPS::lammps MPI::MPI_C)
+
+if(LAMMPS_SOURCE_DIR)
+  include(CheckGeneratorSupport)
+  if(NOT CMAKE_GENERATOR_SUPPORT_FORTRAN)
+    message(STATUS "Skipping Test for the LAMMPS Fortran Module Coupling: no Fortran support in build tool")
+    return()
+  endif()
+
+  include(CheckLanguage)
+  check_language(Fortran)
+
+  if(CMAKE_Fortran_COMPILER AND MPI_Fortran_FOUND AND MPI_Fortran_HAVE_F90_MODULE)
+    enable_language(Fortran)
+
+    if(NOT CMAKE_Fortran_COMPILER_ID)
+      message(STATUS "Skipping Tests for the LAMMPS Fortran Module: cannot identify Fortran compiler")
+      return()
+    endif()
+
+    # GNU Fortran 4.8.x on RHEL/CentOS 7.x is not sufficient to compile the Fortran module.
+    # Work around flang being detected as GNU
+    get_filename_component(_tmp_fc ${CMAKE_Fortran_COMPILER} NAME)
+    if((CMAKE_Fortran_COMPILER_ID STREQUAL "GNU") AND (CMAKE_Fortran_COMPILER_VERSION VERSION_LESS 6.0) AND NOT (_tmp_fc STREQUAL "flang"))
+      message(FATAL_ERROR "Need GNU Fortran compiler version 6.x or later for unit testing")
+    endif()
+
+    get_filename_component(LAMMPS_FORTRAN_MODULE ${LAMMPS_SOURCE_DIR}/../fortran/lammps.f90 ABSOLUTE)
+    add_executable(simpleF90 ${LAMMPS_FORTRAN_MODULE} simple.f90)
+    target_link_libraries(simpleF90 PRIVATE MPI::MPI_Fortran LAMMPS::lammps)
+    if(CMAKE_Fortran_COMPILER_ID STREQUAL "GNU")
+      target_compile_options(simpleF90 PRIVATE -fallow-argument-mismatch)
+    endif()
+
+    get_filename_component(_tmp_fc ${CMAKE_Fortran_COMPILER} NAME)
+    if (_tmp_fc STREQUAL "flang")
+      target_link_libraries(simpleF90 PRIVATE gfortran)
+    endif()
+  endif()
+endif()
diff --git a/examples/COUPLE/simple/simple.f90 b/examples/COUPLE/simple/simple.f90
index 8902104e47..3aafbee01b 100644
--- a/examples/COUPLE/simple/simple.f90
+++ b/examples/COUPLE/simple/simple.f90
@@ -18,8 +18,8 @@
 !   See README for compilation instructions
 
 PROGRAM f_driver
-  USE mpi
   USE liblammps
+  USE mpi
   IMPLICIT NONE
 
   INTEGER, PARAMETER :: fp=20
@@ -129,7 +129,10 @@ PROGRAM f_driver
 
   ! free LAMMPS object
 
-  IF (color == 1) CALL lmp%close()
+  IF (color == 1) THEN
+      CALL lmp%CLOSE()
+      CALL mpi_comm_free(comm_lammps,ierr)
+  END IF
 
   ! close down MPI
 
diff --git a/unittest/c-library/CMakeLists.txt b/unittest/c-library/CMakeLists.txt
index 59f1462e9b..9ca83d1741 100644
--- a/unittest/c-library/CMakeLists.txt
+++ b/unittest/c-library/CMakeLists.txt
@@ -87,6 +87,16 @@ if(BUILD_MPI)
     COMMAND $<TARGET_FILE:simpleC> 1 ${LAMMPS_DIR}/examples/COUPLE/simple/in.lj)
   add_test(NAME RunCoupleSimpleCC
     COMMAND $<TARGET_FILE:simpleCC> 1 ${LAMMPS_DIR}/examples/COUPLE/simple/in.lj)
+
+  find_package(MPI QUIET)
+  if(CMAKE_Fortran_COMPILER AND MPI_Fortran_FOUND AND MPI_Fortran_HAVE_F90_MODULE)
+    add_test(NAME RunCoupleSimpleF90
+      COMMAND $<TARGET_FILE:simpleF90> 1 ${LAMMPS_DIR}/examples/COUPLE/simple/in.lj)
+    set_tests_properties(RunCoupleSimpleF90 PROPERTIES
+      ENVIRONMENT "TSAN_OPTIONS=ignore_noninstrumented_modules=1;HWLOC_HIDE_ERRORS=2"
+      PASS_REGULAR_EXPRESSION "LAMMPS \\([0-9]+ [A-Za-z]+ 2[0-9][0-9][0-9]( - Update [0-9]+)?\\)")
+  endif()
+
   set_tests_properties(RunCoupleSimpleC RunCoupleSimpleCC PROPERTIES
     ENVIRONMENT "TSAN_OPTIONS=ignore_noninstrumented_modules=1;HWLOC_HIDE_ERRORS=2"
     PASS_REGULAR_EXPRESSION "LAMMPS \\([0-9]+ [A-Za-z]+ 2[0-9][0-9][0-9]( - Update [0-9]+)?\\)")