diff --git a/Makefile b/Makefile
index c78765a..a63629d 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@ CFLAGS += -g
 PROFILE = no
 dummy := $(shell $(MAKE) clean)
 else
-CFLAGS += -O2 -DNDEBUG
+CFLAGS += -O3 -DNDEBUG -march=nocona
 endif
 
 all: gc_test