diff --git a/External/SPEC/CFP2017rate/527.cam4_r/CMakeLists.txt b/External/SPEC/CFP2017rate/527.cam4_r/CMakeLists.txt
--- a/External/SPEC/CFP2017rate/527.cam4_r/CMakeLists.txt
+++ b/External/SPEC/CFP2017rate/527.cam4_r/CMakeLists.txt
@@ -91,8 +91,6 @@
   -DSPEC_CASE_FLAG
 )
 
-add_compile_options(-fallow-argument-mismatch)
-
 ## test ########################################################################
 
 speccpu2017_run_test(RUN_TYPE test)
@@ -572,6 +570,12 @@
   zeff.f90
   zenith.F90
 )
+
+check_fortran_compiler_flag("-fallow-argument-mismatch" SUPPORTS_FALLOW_ARGUMENT_MISMATCH)
+if (SUPPORTS_FALLOW_ARGUMENT_MISMATCH)
+  target_compile_options(${PROG} PRIVATE $<$<COMPILE_LANGUAGE:Fortran>:-fallow-argument-mismatch>)
+endif ()
+
 target_link_libraries(${PROG} PRIVATE netcdf)
 
 speccpu2017_prepare_rundir()
diff --git a/cmake/modules/Fortran.cmake b/cmake/modules/Fortran.cmake
--- a/cmake/modules/Fortran.cmake
+++ b/cmake/modules/Fortran.cmake
@@ -27,3 +27,7 @@
       "Please use use Ninja 1.10 or later by adding -G \"Ninja\" to cmake invocation.\n")
   endif()
 endfunction()
+
+# standard CMake Utility Modules specific to Fortran
+# https://cmake.org/cmake/help/latest/manual/cmake-modules.7.html
+include(CheckFortranCompilerFlag)