diff --git a/sch2fig/Makefile b/sch2fig/Makefile
index 70e25b8..091515b 100644
--- a/sch2fig/Makefile
+++ b/sch2fig/Makefile
@@ -18,7 +18,7 @@ LIBS = -lm
 
 include ../common/Makefile.c-common
 
-.PHONY:		test neo900
+.PHONY:		test neo900 test diff view newref
 
 all::		$(NAME)
 
@@ -46,3 +46,14 @@ neo900.pdf:	$(NAME) sch2pdf neo900-template.fig
 		./sch2pdf -o $@ -t neo900-template.fig \
 		    $(NEO900_HW)/neo900.lib $(KICAD_LIBS)/powered.lib \
 		    $(NEO900_HW)/neo900.sch
+
+diff:
+		test/genpng test out
+		test/comp test || $(MAKE) view
+
+view:
+		qiv -t -R -D `echo test/_diff*.png | \
+		    sed 's/\([^ ]*\)_diff\([^ ]*\)/\1_diff\2 \1ref\2 \1out\2/g'`
+
+newref:
+		test/genpng test ref