BSD tar cannot handle the StyleTar.tar.gz file:
tar: Cannot identify format. Searching...
tar: Cpio file name length 20804 is out of range
tar: Invalid header, starting valid header search.
tar: Cpio file name length 59038 is out of range

Index: themes/Makefile.in
--- themes/Makefile.in.orig
+++ themes/Makefile.in
@@ -39,9 +39,7 @@ THEMES := StyleTab absolute-e Crux microGUI mxflat Elb
 
 all :
 	for d in $(THEMES); do \
-		( tar --help|grep -q sort= && rbopts=--sort=name ; \
-	          tar --help|grep -q 'GNU tar' && rbopts="$$rbopts --format=gnu --mtime @1" ; \
-		  cd $(srcdir) && LC_ALL=C tar $$rbopts -c $$d/* | gzip -n9 > $$d.tar.gz ) ; \
+		( cd $(srcdir) && LC_ALL=C tar -f - -c $$d/* | gzip -n9 > $$d.tar.gz ) ; \
 	done
 
 install : all installdirs
@@ -51,7 +49,7 @@ install : all installdirs
 	done
 	@# Don't use tar for StyleTab. It's not compression, but tar
 	@# itself slows in librep.
-	cd $(DESTDIR)$(themedir) && tar xf StyleTab.tar.gz && rm StyleTab.tar.gz
+	cd $(DESTDIR)$(themedir) && ${LOCALBASE}/bin/gtar xf StyleTab.tar.gz && rm StyleTab.tar.gz
 
 installdirs : $(top_srcdir)/mkinstalldirs
 	$(SHELL) $< $(DESTDIR)$(themedir)