Don't override Gentoo's default _FORTIFY_SOURCE.
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -426,7 +426,7 @@ if (ENABLE_ASAN OR ENABLE_UBSAN)
 endif()
 
 # try to ensure some compiler sanity and hardening options where supported
-foreach (flag -fno-strict-overflow -fno-delete-null-pointer-checks -fhardened)
+foreach (flag -fno-strict-overflow -fno-delete-null-pointer-checks)
 	check_c_compiler_flag(${flag} found)
 	if (found)
 		add_compile_options(${flag})