--- Makefile.orig	2017-02-11 22:31:35 UTC
+++ Makefile
@@ -1,10 +1,12 @@
-CC=gcc
-CFLAGS=-g -Wall -O2 -Wno-unused-function
+CC ?=		gcc
+CFLAGS ?=	-g -Wall -O2 -Wno-unused-function
+LDFLAGS +=	-lz -lm
 
-all:trimadap-mt
+all: trimadap-mt
 
 trimadap-mt:trimadap-mt.c ksw.c kthread.c kseq.h ksw.h
-		$(CC) $(CFLAGS) -pthread ksw.c kthread.c trimadap-mt.c -o $@ -lz -lm
+	$(CC) $(CFLAGS) -pthread ksw.c kthread.c trimadap-mt.c -o $@ $(LDFLAGS)
 
 clean:
-		rm -fr gmon.out *.o ext/*.o a.out seqtk trimadap *~ *.a *.dSYM session* trimadap-mt
+	rm -fr gmon.out *.o ext/*.o a.out seqtk trimadap *~ *.a \
+		*.dSYM session* trimadap-mt