--- a/Makefile
+++ b/Makefile
@@ -4,11 +4,11 @@
 
 default: build/debug/mujs build/debug/mujs-pp
 
-CFLAGS = -std=c99 -pedantic -Wall -Wextra -Wno-unused-parameter
+CFLAGS ?= -std=c99 -pedantic -Wall -Wextra -Wno-unused-parameter
 
 OPTIM = -O3
 
-prefix = /usr/local
+prefix ?= /usr/local
 bindir = $(prefix)/bin
 incdir = $(prefix)/include
 libdir = $(prefix)/lib
@@ -33,7 +33,7 @@ HDRS = mujs.h jsi.h regexp.h utf.h astnames.h opnames.h utfdata.h
 
 ifneq ($(HAVE_READLINE),no)
   READLINE_CFLAGS = -DHAVE_READLINE
-  READLINE_LIBS = -lreadline
+  READLINE_LIBS = $(LDFLAGS) -lreadline
 endif
 
 SRCS = \