support margins

Signed-off-by: Mattias Andrée <maandree@member.fsf.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/png.c b/src/png.c
index ad889e1..504cdf0 100644
--- a/src/png.c
+++ b/src/png.c
@@ -71,6 +71,7 @@ save_png (int fbfd, long width, long height, int imgfd, void *restrict data)
     goto fail;
   
   /* Initialise PNG write, and write head. */
+  errno = 0;
   if (setjmp (png_jmpbuf(pngbuf))) /* Failing libpng calls jump here. */
     goto fail;
   png_init_io (pngbuf, file);