The BSD version of head does not accept the --bytes option,
nor does it accept negative integers. Use dd instead for
BSD support.

--- a/tests/makefile	2014-05-16 05:46:53.000000000 -0500
+++ b/tests/makefile	2018-03-18 18:29:47.000000000 -0500
@@ -103,10 +103,10 @@
 
 giffix-rebuild:
 	@echo "Rebuilding giffix test."
-	@head --bytes=-20 <$(PICS)/treescap.gif | $(UTILS)/giffix 2>/dev/null | $(UTILS)/gifbuild -d >giffixed.ico
+	@dd if=$(PICS)/treescap.gif bs=1 count=387 | $(UTILS)/giffix 2>/dev/null | $(UTILS)/gifbuild -d >giffixed.ico
 giffix-regress:
 	@echo "giffix: Testing giffix behavior"
-	@head --bytes=-20 <$(PICS)/treescap.gif | $(UTILS)/giffix 2>/dev/null | $(UTILS)/gifbuild -d | diff -u giffixed.ico -
+	@dd if=$(PICS)/treescap.gif bs=1 count=387 | $(UTILS)/giffix 2>/dev/null | $(UTILS)/gifbuild -d | diff -u giffixed.ico -
 
 gifinto-regress:
 	@echo "gifinto: Checking behavior on short files."