diff --git a/CMakeLists.txt b/CMakeLists.txt
index cba7670..3dd4e3f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -187,7 +187,7 @@ function(give_options_without_warnings target)
 
         target_compile_definitions(${target} PRIVATE
                                              $<$<BOOL:${TWN_FEATURE_DYNLIB_GAME}>:TWN_FEATURE_DYNLIB_GAME>
-                                             _GNU_SOURCE)
+                                             $<$<BOOL:${LINUX}>:_GNU_SOURCE>)
 endfunction()