diff --git a/Tests/FortranOnly/CMakeLists.txt b/Tests/FortranOnly/CMakeLists.txt
index 1b2651dd7..9bf03033a 100644
--- a/Tests/FortranOnly/CMakeLists.txt
+++ b/Tests/FortranOnly/CMakeLists.txt
@@ -65,6 +65,13 @@ if(NOT CMAKE_Fortran_COMPILER_ID STREQUAL XL)
     message(SEND_ERROR "CHECK_Fortran_SOURCE_COMPILES for HAVE_PRINT failed:\n"
       "${err}")
   endif()
+
+  unset(Fortran_BOGUS_FLAG CACHE)
+  include(CheckFortranCompilerFlag)
+  CHECK_Fortran_COMPILER_FLAG(-_this_is_not_a_flag_ Fortran_BOGUS_FLAG)
+  if (Fortran_BOGUS_FLAG)
+    message (SEND_ERROR "CHECK_Fortran_COMPILER_FLAG() succeeded, but should have failed")
+  endif ()
 endif()
 
 # Test generation of preprocessed sources.