diff --git a/Makefile.sphinx b/Makefile.sphinx
--- a/Makefile.sphinx
+++ b/Makefile.sphinx
@@ -31,8 +31,14 @@
 endif
 
 sphinx/clean:
+	if [ -f "$(CURDIR)/images/Makefile" ]; then \
+		make -C $(CURDIR)/images/ clean; \
+	fi
 	$(SPHINXBUILD) -M clean $(SPHINX_SRCDIR) $(SPHINX_BUILDDIR) $(SPHINXOPTS)
 sphinx/%: $(apidoc_dep)
+	if [ -f "$(CURDIR)/images/Makefile" ]; then \
+		make -C $(CURDIR)/images/ $@; \
+	fi
 	$(SPHINXBUILD) -b $* $(SPHINX_SRCDIR) $(SPHINX_BUILDDIR)/$* $(SPHINXOPTS)
 
 apidoc: $(apidoc_dep)
@@ -42,7 +48,7 @@
 	find $(shell pwd)/apidoc -name "*.rst" | xargs sed -i '1i:orphan:\n'
 	touch $@
 
-.PHONY: clean clean-apidoc
+.PHONY: clean clean-apidoc sphinx/clean
 clean: sphinx/clean clean-apidoc
 clean-apidoc:
 	rm -rf $(APIDOC_DIR)