diff --git a/doc/Makefile b/doc/Makefile
index 07cee7449..89b01a085 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -18,6 +18,7 @@ help:
 	@echo "  html      to make standalone HTML files"
 	@echo "  dirhtml   to make HTML files called index.html in directories"
 	@echo "  pickle    to make pickle files"
+	@echo "  json      to make json files"
 	@echo "  htmlhelp  to make HTML files and a HTML help project"
 	@echo "  latex     to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
 	@echo "  changes   to make an overview over all changed/added/deprecated items"
@@ -48,6 +49,10 @@ pickle:
 	mkdir -p _build/pickle _build/doctrees
 	$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) _build/pickle
 
+json:
+	mkdir -p _build/json _build/doctrees
+	$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) _build/json
+
 htmlhelp:
 	mkdir -p _build/htmlhelp _build/doctrees
 	$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) _build/htmlhelp