diff --git a/README.md b/README.md
index 3f679fb..60ea752 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ include/              Your headers. Headers do not mix with implementations.
 src/                  Said implementations.
 Makefile              Or configure.ac + Makefile.am (autogen.sh is required for autotools).
 bin/{release,debug}   Debugging should be in the workflow. Nothing is bug free. Release is
-                      ALWAYS -O2 or -O1, unless you give a damn good reason why it isn't.
+                      ALWAYS -Os (or z) or -O1, unless you give a damn good reason why it isn't.
                       Examples include: compiler bugs, breaking optimizations.
 benchmarks/           You MUST benchmark your software. If it isn't memory-lean, it's not
                       going in Null Linux. Benchmarks can be done any way, but should have