diff --git a/Makefile b/Makefile
index ce1f747..a5a7e2f 100644
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,7 @@ VPATH = $(SPATH) $(IPATH) $(DPATH) $(OPATH)
 
 # compiler and compiler flags
 CC = g++
-CFLAGS = -I$(IPATH) -std=c++11
+CFLAGS = -I$(IPATH) -std=c++11 -Os
 
 # list of object files
 SOURCES = $(wildcard $(SPATH)/*.$(STYPE))