Fix compile error

Signed-off-by: Dongjin Kim <tobetter@gmail.com>
diff --git a/Makefile b/Makefile
index 5500e70..62027f9 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,7 @@
 all:
 	make -C ./meson
-	make -C ./drm-setcrtc
\ No newline at end of file
+	make -C ./drm-setcrtc
+
+clean:
+	make -C ./meson clean
+	make -C ./drm-setcrtc clean