diff --git a/Makefile b/Makefile
index 4b4b074c..927e1fee 100644
--- a/Makefile
+++ b/Makefile
@@ -53,7 +53,7 @@ clean:
 
 .PHONY: html
 html:
-	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
+	$(SPHINXBUILD) -b html -j auto $(ALLSPHINXOPTS) $(BUILDDIR)/html
 	@echo
 	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."