--- ./makefile.orig
+++ ./makefile
@@ -1,6 +1,5 @@
-# point it to where the compiler can find the Lua header files (lua.h, etc.)
-# LUADIR = ../lua
-LUADIR = /usr/include/lua5.1/
+LUAPC?=lua5.1
+LUA_CFLAGS = $(shell pkg-config --cflags $(LUAPC))
 
 # define your own "large" integer type; not defining a proper type
 # will default to 'long', which may cause problems with 'size_t'
@@ -16,8 +15,8 @@
         -Wshadow \
         -Wwrite-strings
 
-CFLAGS = -D_POSIX_SOURCE $(CWARNS) $(INTTYPE) -O2 -I$(LUADIR)
-CC = gcc
+OPT_CFLAGS ?= -O2
+CFLAGS = -D_POSIX_SOURCE $(CWARNS) $(INTTYPE) $(OPT_CFLAGS) $(LUA_CFLAGS)
 
 struct.so: struct.c makefile
 	$(CC) $(CFLAGS) -shared -fpic -o struct.so struct.c