diff --git a/Makefile b/Makefile
index a86a40d..7af4ea4 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,7 @@
 .PHONY: www/js/escalator.js
 
 www/js/escalator.js: $(shell find src -name "*.js")
+	mkdir -p www/js
 	cat \
 		src/open.js \
 		src/box.js \