#ifdef HAVE_XRENDER
if (dpyinfo->pict_format)
{
- get_bits_and_offset (((unsigned long) dpyinfo->pict_format->direct.alphaMask
- << dpyinfo->pict_format->direct.alpha),
- &dpyinfo->alpha_bits, &dpyinfo->alpha_offset);
+ unsigned long channel_mask
+ = ((unsigned long) dpyinfo->pict_format->direct.alphaMask
+ << dpyinfo->pict_format->direct.alpha);
+
+ if (channel_mask)
+ get_bits_and_offset (channel_mask, &dpyinfo->alpha_bits,
+ &dpyinfo->alpha_offset);
}
else
#endif