preview png, actually make it a png

diff --git a/Makefile b/Makefile
index 29f09bc16f805c5006db2c40b958313f8b3b1e36..97f112b4b8c828e7c62b8ecc535f34fca77096be 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -142,7 +142,7 @@ minprintable-%.ps: $(BOARDDEPS)
        ./generate-board -Xp$*,bPrintableAll faces.plag input-graph $o
 
 %-preview.png: %.pdf Makefile
-       gm convert -geometry 50% $< $@.tmp && $i
+       gm convert -geometry 50% $< png:$@.tmp && $i
 
 boundings-%.ps: $(BOARDDEPS)
        ./generate-board -XB$* faces.plag input-graph $o