diff -uNr pigz-2.4/Makefile pigz-2.4.mod/Makefile
--- pigz-2.4/Makefile	2017-12-27 02:35:01.000000000 +0200
+++ pigz-2.4.mod/Makefile	2019-09-23 22:45:25.088019565 +0300
@@ -1,7 +1,7 @@
-CC=gcc
-CFLAGS=-O3 -Wall -Wextra -Wno-unknown-pragmas
-LDFLAGS=
-LIBS=-lm -lpthread -lz
+CC?=gcc
+CFLAGS+=-Wall -Wextra -Wno-unknown-pragmas
+LDFLAGS?=
+LIBS=-lz -lm
 ZOPFLI=zopfli/src/zopfli/
 ZOP=deflate.o blocksplitter.o tree.o lz77.o cache.o hash.o util.o squeeze.o katajainen.o