https://github.com/davidgiven/wordgrinder/issues/150
--- Makefile.orig	2020-10-23 16:48:53.000000000 -0500
+++ Makefile	2020-11-06 23:52:53.000000000 -0600
@@ -47,7 +47,7 @@
 FILEFORMAT := 8
 
 ifdef SOURCE_DATE_EPOCH
-       DATE := $(shell LC_ALL date --utc --date="@$(SOURCE_DATE_EPOCH)" +'%-d %B %Y')
+       DATE := $(shell LC_ALL=C gdate --utc --date="@$(SOURCE_DATE_EPOCH)" +'%-d %B %Y')
 else
        DATE := $(shell date +'%-d %B %Y')
 endif