diff --git a/Makefile b/Makefile
index 5071a1a..96f7138 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,5 @@
 current_dir := $(shell pwd)
+SRCS := $(wildcard tools/xkremap/*.[ch])
 .PHONY: all
 
 all: xkremap
@@ -10,5 +11,5 @@ mruby:
 	curl -L --fail --retry 3 --retry-delay 1 https://github.com/mruby/mruby/archive/1.2.0.tar.gz -s -o - | tar zxf -
 	mv mruby-1.2.0 $@
 
-mruby/build/host/bin/xkremap: mruby build_config.rb tools/xkremap/main.c tools/xkremap/remap.c tools/xkremap/xkremap.h
+mruby/build/host/bin/xkremap: mruby build_config.rb $(SRCS)
 	cd mruby && MRUBY_CONFIG="$(current_dir)/build_config.rb" make