diff --git a/makefile b/makefile
index b506b46..7d1f50d 100755
--- a/makefile
+++ b/makefile
@@ -6,7 +6,7 @@ cc_mips24kc_le=/toolchains/lede-sdk-17.01.2-ramips-mt7621_gcc-5.4.0_musl-1.1.16.
 #cc_arm= /toolchains/gcc-linaro-4.9.4-2017.01-x86_64_arm-linux-gnueabi/bin/arm-linux-gnueabi-g++ -march=armv6 -marm 
 cc_arm= /toolchains/arm-2014.05/bin/arm-none-linux-gnueabi-g++
 #cc_bcm2708=/home/wangyu/raspberry/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-g++ 
-FLAGS= -std=c++11   -Wall -Wextra -Wno-unused-variable -Wno-unused-parameter -Wno-missing-field-initializers
+FLAGS= -std=c++11   -Wall -Wextra -Wno-unused-variable -Wno-unused-parameter -Wno-missing-field-initializers ${OPT}
 
 SOURCES=main.cpp log.cpp common.cpp lib/fec.cpp lib/rs.cpp packet.cpp delay_manager.cpp fd_manager.cpp connection.cpp fec_manager.cpp misc.cpp tunnel_client.cpp tunnel_server.cpp my_ev.cpp -isystem libev