diff --git a/mkfont.c b/mkfont.c
index 48f81d6..c01bffc 100644
--- a/mkfont.c
+++ b/mkfont.c
@@ -93,7 +93,7 @@ int writepng( const char *filename, uint8_t *fdata, int w, int h, int p )
 		PNG_FILTER_TYPE_DEFAULT);
 	if ( xupshift )
 	{
-		uint32_t grabs[2] = {0,endianswap(-xupshift)};
+		uint32_t grabs[2] = {0,endianswap(xupshift)};
 		png_unknown_chunk grab =
 		{
 			.name = "grAb",