diff --git a/docs/Makefile b/docs/Makefile
index d7c176a..5729d9e 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -1,49 +1,56 @@
 SPHINXOPTS =
 SPHINXBUILD = python3 -c 'import sphinx, sys; sys.exit(sphinx.main(sys.argv))'
 SOURCEDIR = .
 BUILDDIR = _build
 HTMLDIR = $(BUILDDIR)/html
 
 INSTALL_HOST = pergamon.internal.softwareheritage.org
 INSTALL_DIR = /srv/softwareheritage/docs/webroot/devel
 INSTALL_GROUP = swhdev
 INSTALL_PERMS = g+rwX
 
 
 html: sphinx/html
-sphinx/html: links-stamp apidoc-stamp images-stamp
+sphinx/html: links-stamp apidoc-stamp images-stamp rec-build-stamp
 
 links-stamp:
 	bin/ln-sphinx-subprojects
 	touch $@
 
 apidoc-stamp:
 	$(MAKE) -C ../../ docs-apidoc
 	touch $@
 
 images-stamp:
 	$(MAKE) -C images
 	touch $@
 
+# Build documentation recursively in all packages, to make sure that auxiliary,
+# non-sphinx managed documentation artifacts (e.g., schema diagrams) are also
+# built.
+rec-build-stamp: $(wildcard ../../swh-*/docs/*.rst)
+	$(MAKE) -C ../../ docs
+	touch $@
+
 clean: sphinx/clean
 	bin/ln-sphinx-subprojects --remove
 	$(MAKE) -C images clean
 	rm -f *-stamp
 
 distclean: clean
 	make -C ../../ docs-clean
 
 help: sphinx/help
 
 sphinx/%:
 	@$(SPHINXBUILD) -M $* "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
 
 install: html
 	test -d $(HTMLDIR)
 	rsync -rlvuz --delete $(BUILDDIR)/html/ $(INSTALL_HOST):$(INSTALL_DIR)/
 	ssh $(INSTALL_HOST) \
 		"find $(INSTALL_DIR) -not -group $(INSTALL_GROUP) -exec chgrp -v $(INSTALL_GROUP) {} + ; \
 		 find $(INSTALL_DIR) -not -perm -ug=rw,o=r -exec chmod -v ug+rw,o+r {} + ; \
 		 find $(INSTALL_DIR) -type d -not -perm -g=xs,ou=x -exec chmod -v g+xs,ou+x {} +"
 
 .PHONY: help html clean distclean install