--- src/hid/png/png.c.orig	2010-07-19 15:36:17.000000000 +0200
+++ src/hid/png/png.c	2010-07-19 15:37:53.000000000 +0200
@@ -137,6 +137,8 @@
   NULL
 };
 
+#define NUM_FILETYPES (sizeof(filetypes)/sizeof(filetypes[0]) - 1)
+
 HID_Attribute png_attribute_list[] = {
   /* other HIDs expect this to be first.  */
   {"outfile", "Graphics output file",
@@ -176,7 +178,7 @@
 #define HA_use_alpha 8
 
   {"format", "Graphics file format",
-   HID_Enum, 0, 0, {2, 0, 0}, filetypes, 0},
+   HID_Enum, 0, 0, {NUM_FILETYPES-1, 0, 0}, filetypes, 0},
 #define HA_filetype 9
 
   {"png-bloat", "Amount (in/mm/mil/pix) to add to trace/pad/pin edges (1 = 1/100 mil)",