--- wikisrc/pkgsrc/hardening.mdwn	2017/11/07 01:52:37	1.27
+++ wikisrc/pkgsrc/hardening.mdwn	2017/11/07 02:00:44	1.28
@@ -136,6 +136,13 @@ Just like with `PKGSRC_MKPIE` above, thi
 crash, usually indicating an actual bug in the program. The fix will typically
 involve patching the original program.
 
+### Optimization is required
+
+At least in the case of GCC, FORTIFY will only be applied if optimization is
+applied while compiling. This means that the CFLAGS should also contain -O, -O2
+or another optimization level. This cannot easily be applied globally, as some
+packages may require specific optimization levels.
+
 ## Problems with `PKGSRC_USE_RELRO`
 
 ### Performance impact