diff -u -r -N my_basic/makefile my_basic-makefile/makefile
--- my_basic/makefile	2018-08-28 20:17:25.725132293 +0200
+++ my_basic-makefile/makefile	2018-08-28 20:32:42.807023449 +0200
@@ -1,3 +1,5 @@
+CFLAGS=-Os
+
 OS := $(shell uname -s)
 IS_APPLE := $(shell echo $(OS)|grep -i darwin)
 
@@ -10,10 +12,10 @@
 endif
 
 main.o : shell/main.c core/my_basic.h
-	cc -Os -c shell/main.c -Wno-unused-result
+	cc $(CFLAGS) -c shell/main.c -Wno-unused-result
 
 my_basic.o : core/my_basic.c core/my_basic.h
-	cc -Os -c core/my_basic.c -Wno-multichar -Wno-overflow -Wno-unused-result
+	cc $(CFLAGS) -c core/my_basic.c -Wno-multichar -Wno-overflow -Wno-unused-result
 
 clean :
 	rm -f main.o my_basic.o output/my_basic_bin output/my_basic_bin.exe