diff --git a/Makefile.sphinx b/Makefile.sphinx
index 2d2497c..941ed3e 100644
--- a/Makefile.sphinx
+++ b/Makefile.sphinx
@@ -1,39 +1,41 @@
 # Makefile to be included by other modules, from the TOPLEVEL/docs/ dir, to
 # automatically build sphinx documentation.
 
 APIDOC_DIR = apidoc
 APIDOC_OPTS = --implicit-namespaces
+SPHINXBUILD = python3 -c 'import sphinx, sys; sys.exit(sphinx.main(sys.argv))'
+SPHINXAPIDOC = python3 -c 'import sphinx.apidoc, sys; sys.exit(sphinx.apidoc.main(sys.argv))'
 SPHINX_OPTS =
 SPHINX_BUILDDIR = _build
 SPHINX_SRCDIR = .
 
 # relative to docs/ dir. Hence "." exclude the docs/ dir itself
 APIDOC_EXCLUDES =
 APIDOC_EXCLUDES += . ../setup.py
 APIDOC_EXCLUDES += '../swh/*/tests/*' '../swh/*/*/tests/*' '../swh/*/*/*/tests/*'
 APIDOC_EXCLUDES += '../bin/*'
 APIDOC_EXCLUDES += '../utils/*'
 
 html: sphinx/html
 help: sphinx/help
 
 sphinx/clean:
-	sphinx-build -M clean $(SPHINX_SRCDIR) $(SPHINX_BUILDDIR) $(SPHINXOPTS)
+	$(SPHINXBUILD) -M clean $(SPHINX_SRCDIR) $(SPHINX_BUILDDIR) $(SPHINXOPTS)
 sphinx/%: apidoc-stamp
-	sphinx-build -M $* $(SPHINX_SRCDIR) $(SPHINX_BUILDDIR) $(SPHINXOPTS)
+	$(SPHINXBUILD) -M $* $(SPHINX_SRCDIR) $(SPHINX_BUILDDIR) $(SPHINXOPTS)
 
 apidoc: apidoc-stamp
 apidoc-stamp:
-	sphinx-apidoc $(APIDOC_OPTS) -o $(APIDOC_DIR) .. $(APIDOC_EXCLUDES)
+	$(SPHINXAPIDOC) $(APIDOC_OPTS) -o $(APIDOC_DIR) .. $(APIDOC_EXCLUDES)
 	touch $@
 
 .PHONY: clean clean-apidoc
 clean: sphinx/clean clean-apidoc
 clean-apidoc:
 	rm -rf $(APIDOC_DIR)
 	rm -f *-stamp
 
 
 # Local Variables:
 # mode: makefile
 # End:
diff --git a/docs/Makefile b/docs/Makefile
index c896264..a65b996 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -1,50 +1,50 @@
 SPHINXOPTS =
-SPHINXBUILD = sphinx-build
+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
 
 links-stamp:
 	bin/ln-sphinx-subprojects
 	touch $@
 
 apidoc-stamp:
 	$(MAKE) -C ../../ docs-apidoc
 	touch $@
 
 images-stamp:
 	$(MAKE) -C images
 	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
 	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
 
 sphinx/%:
 	@$(SPHINXBUILD) -M $* "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
 
 install: html
 	test -d $(HTMLDIR)
 	rsync -avuz $(BUILDDIR)/html/ $(INSTALL_HOST):$(INSTALL_DIR)/
 	ssh $(INSTALL_HOST) \
 		"chgrp -R $(INSTALL_GROUP) $(INSTALL_DIR) ; \
 		 chmod -R $(INSTALL_PERMS) $(INSTALL_DIR) ; \
 		 find $(INSTALL_DIR) -type d -exec chmod g+s {} +"
 
 .PHONY: help html clean distclean install