fix that must be submitted to the upstream maintainer
--- a/manual/split/makefile
+++ b/manual/split/makefile
@@ -5,10 +5,11 @@
 #TTH=../tth
 
 index.html : ../tth_manual.tex
-	$(TTH) -s -e2 <../tth_manual.tex -L../tth_manual -p../ | ../../tools/tthsplit
+	$(LATEX) ../tth_manual.tex
+	$(TTH) -s -e2 <../tth_manual.tex -L./tth_manual | ../../tools/tthsplit
 
 tidy :
 	rm -f *.log *.idx *.ilg *.toc *.out *.dvi *.lyx *.tms *.tid *.tin *.ind
 
 clean :
-	rm -f *.log *.idx *.ilg *.html *.toc *.out *.dvi *.lyx *.tms *.tid *.tin *.ind *.aux
\ No newline at end of file
+	rm -f *.log *.idx *.ilg *.html *.toc *.out *.dvi *.lyx *.tms *.tid *.tin *.ind *.aux