diff --git a/make/tex.mk b/make/tex.mk
index 3b37a7e8..9a68531d 100644
--- a/make/tex.mk
+++ b/make/tex.mk
@@ -12,6 +12,8 @@ endif
 latex = latex
 PDFLATEX = pdflatex
 PDF_VIEWER ?= $(firstword $(shell which okular kpdf acroread))
+CAT ?= cat
+SED ?= sed
 
 # this is what is there already
 PRE_FIG_LOCAL = $(wildcard *.fig)