$(Q)a2x -f manpage -D $(o)/isolate $<
$(Q)$(call symlink,$@,run/$(MAN1DIR))
-$(o)/isolate/isolate.1.html: $(s)/isolate/isolate.1.txt
+# The dependency on isolate.1 is there to serialize both calls of asciidoc,
+# which does not name temporary files safely.
+$(o)/isolate/isolate.1.html: $(s)/isolate/isolate.1.txt $(o)/isolate/isolate.1
$(M)"HTML $<"
$(Q)a2x -f xhtml -D $(o)/isolate $<