diff --git a/Makefile b/Makefile
index 0a60ccc..ac13e21 100644
--- a/Makefile
+++ b/Makefile
@@ -1,13 +1,13 @@
-CC=gcc
-CFLAGS=-g -Wall -O2 -Wno-unused-function
+CC ?= gcc
+CFLAGS+=-g -Wall -O2 -Wno-unused-function
 BINDIR=/usr/local/bin
 
-all:seqtk
+all: seqtk
 
-seqtk:seqtk.c khash.h kseq.h
-		$(CC) $(CFLAGS) seqtk.c -o $@ -lz -lm
+seqtk: seqtk.c khash.h kseq.h
+		$(CC) $(LDFLAGS) $(CFLAGS) $(CPPFLAGS) seqtk.c -o $@ -lz -lm
 
-install:all
+install: all
 		install seqtk $(BINDIR)
 
 clean: