diff --git a/Makefile b/Makefile
index 1bb2250..910fb9e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,12 +1,13 @@
 VERSION=$(shell jq -r .version package.json)
 DATE=$(shell date +%F)
+SRCDIR ?= demo
 
 all: index.html
 
 clean:
 	rm -f index.html
 
-index.html: demo/index.md demo/template.html Makefile
-	pandoc --toc -s --css src/reset.css --css src/index.css -Vversion=v$(VERSION) -Vdate=$(DATE) -i $< -o $@ --template=demo/template.html
+index.html: $(SRCDIR)/index.md $(SRCDIR)/template.html Makefile
+	pandoc --toc -s --css src/reset.css --css src/index.css -Vversion=v$(VERSION) -Vdate=$(DATE) -i $< -o $@ --template=$(SRCDIR)/template.html
 
 .PHONY: all clean