diff --git a/Makefile.rule b/Makefile.rule
index 85abf584b..b73f87d68 100644
--- a/Makefile.rule
+++ b/Makefile.rule
@@ -108,19 +108,16 @@ VERSION = 0.2.2
 # The installation directory.
 # PREFIX = /opt/OpenBLAS
 
-# Common Optimization Flag; -O2 is enough.
-# DEBUG = 1
-
-ifeq ($(DEBUG), 1)
-COMMON_OPT += -g
-# -DDEBUG
-else
-COMMON_OPT += -O2
-endif
+# Common Optimization Flag; 
+# The default -O2 is enough.
+# COMMON_OPT = -O2
 
 # Profiling flags
 COMMON_PROF = -pg
 
+# Build Debug version
+# DEBUG = 1
+
 #
 #  End of user configuration 
 #
diff --git a/Makefile.system b/Makefile.system
index 63d3577a7..b2180f30d 100644
--- a/Makefile.system
+++ b/Makefile.system
@@ -687,6 +687,15 @@ AWK	= awk
 REVISION = -r$(VERSION)
 MAJOR_VERSION = $(word 1,$(subst ., ,$(VERSION)))
 
+ifeq ($(DEBUG), 1)
+COMMON_OPT += -g
+endif
+
+ifndef COMMON_OPT
+COMMON_OPT = -O2
+endif
+
+
 CFLAGS     = $(COMMON_OPT) $(CCOMMON_OPT) -I$(TOPDIR)
 PFLAGS     = $(COMMON_OPT) $(CCOMMON_OPT) -I$(TOPDIR) -DPROFILE $(COMMON_PROF)