diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 05d090ff0..692730db1 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -234,10 +234,8 @@ endif(OPENGL_FOUND)
 #   Its sole purpose is to issue compilation warnings during build time if
 #   variables are shadowed in public headers.
 
-fl_debug_var(CMAKE_CXX_COMPILER_ID)
-if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR
-   CMAKE_CXX_COMPILER_ID STREQUAL "Clang" OR
-   CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
+set(_compilers GNU Clang AppleClang)
+if(CMAKE_CXX_COMPILER_ID IN_LIST _compilers)
 
   set(include_all "${CMAKE_CURRENT_BINARY_DIR}/include_all.h")
   file(WRITE ${include_all} "/* DO NOT EDIT - this file is created by CMake */\n")
@@ -259,6 +257,7 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR
   set_target_properties(shadow_variables PROPERTIES COMPILE_FLAGS -Wshadow)
 
 endif() # GNU or Clang (-Wshadow test)
+unset(_compilers)
 
 
 # *** EXPERIMENTAL ***