diff --git a/make/tex.mk b/make/tex.mk
index 10321417..ecd38493 100644
--- a/make/tex.mk
+++ b/make/tex.mk
@@ -106,7 +106,8 @@ LATEX_INPUT = $(TEX) $(EPS)
 HTML_INPUT  = $(HTML) $(IMAGES)
 
 # this comes in handy
-DATE := $(if $(DATE),$(DATE),$(shell date +'%b, %d, %Y'))
+DATE_FORMAT ?= '%b, %d, %Y'
+DATE := $(if $(DATE),$(shell date +$(DATE_FORMAT) --date $(DATE)),$(shell date +$(DATE_FORMAT)))
 TEX_WARN_DONT_EDIT = "\
 %+---------------------------------------------------+\n\
 %|            DO NOT EDIT THIS FILE!                 |\n\