Index: cmake/DrawdanceCompilerOptions.cmake
--- cmake/DrawdanceCompilerOptions.cmake.orig
+++ cmake/DrawdanceCompilerOptions.cmake
@@ -44,7 +44,4 @@ else()
         $<$<COMPILE_LANGUAGE:CXX>:-fno-exceptions>
         $<$<COMPILE_LANGUAGE:C>:-Wstrict-prototypes>
     )
-	if(UNIX AND NOT APPLE)
-		add_compile_definitions(_XOPEN_SOURCE=600)
-	endif()
 endif()
