Index: ffcx/doc/Makefile
===================================================================
--- ffcx.orig/doc/Makefile	2021-03-09 11:07:15.589349230 +0100
+++ ffcx/doc/Makefile	2021-03-09 11:14:35.917653550 +0100
@@ -12,6 +12,9 @@
 help:
 	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
 
+clean:
+	@rm -rf "$(SOURCEDIR)"/_autogenerated "$(BUILDDIR)"
+
 .PHONY: help Makefile
 
 # Catch-all target: route all unknown targets to Sphinx using the new