diff --git a/Makefile b/Makefile
index dd18365..c602776 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 CXX = g++
-CXXFLAGS = -Wall
+CXXFLAGS = -Wall -O3
 
 mc: main.o Timing.o
 	$(CXX) $(CXXFLAGS) -o mc main.o Timing.o