diff --git a/Makefile b/Makefile
index 2b502d78bf7d6da7322b46b12896881baf2b48e3..9e0e49f50b690f7dcb70887558f94da850576d53 100644
--- a/Makefile
+++ b/Makefile
@@ -43,7 +43,7 @@ $(CSS_OBJ): www/less/search.less $(LESSC) $(LESSHAT) $(WDN_MIXINS)
 	$(LESSC) --clean-css $< $@
 	
 $(LESSC):
-	npm install less
+	npm install less less-plugin-clean-css
 
 $(LESS_LIB)/%.less:
 	@mkdir -p $(@D)