diff --git a/scripts/makefile.dj2 b/scripts/makefile.dj2
index a43f34a..e59c432 100644
--- a/scripts/makefile.dj2
+++ b/scripts/makefile.dj2
@@ -19,6 +19,13 @@
 
 RANLIB=ranlib
 
+CP=cp
+RM_F=rm -f
+
+# Pre-built configuration
+# See scripts/pnglibconf.mak for more options
+PNGLIBCONF_H_PREBUILT = scripts/pnglibconf.h.prebuilt
+
 OBJS = png.o pngset.o pngget.o pngrutil.o pngtrans.o pngwutil.o \
 	pngread.o pngrio.o pngwio.o pngwrite.o pngrtran.o pngwtran.o \
 	pngmem.o pngerror.o pngpread.o
@@ -28,9 +35,8 @@
 
 all: libpng.a pngtest
 
-# see scripts/pnglibconf.mak for more options
-pnglibconf.h: scripts/pnglibconf.h.prebuilt
-	cp scripts/pnglibconf.h.prebuilt $@
+pnglibconf.h: $(PNGLIBCONF_H_PREBUILT)
+	$(CP) $(PNGLIBCONF_H_PREBUILT) $@
 
 libpng.a: $(OBJS)
 	ar rc $@  $(OBJS)
@@ -43,7 +49,7 @@
 test: pngtest
 	./pngtest
 clean:
-	rm -f *.o libpng.a pngtest pngout.png pnglibconf.h
+	$(RM_F) *.o libpng.a pngtest pngout.png pnglibconf.h
 
 # DO NOT DELETE THIS LINE -- make depend depends on it.