--- a/Makefile	Wed Jun 27 23:06:14 2018 +0800
+++ b/Makefile	Wed Jun 27 23:09:16 2018 +0800
@@ -98,3 +98,7 @@
 	    'uikit-$(uikit_version)/css/*.min.css' \
 	    'uikit-$(uikit_version)/js/' \
 	    'uikit-$(uikit_version)/fonts/'
+
+.PHONY: clean
+clean:
+	if test -d $(libs); then rm -r $(libs); fi