diff --git a/pngpread.c b/pngpread.c
index 0169ecb..4fce7c0 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -234,6 +234,7 @@ png_push_read_chunk(png_structrp png_ptr, png_inforp info_ptr)
png_error(png_ptr, "Missing PLTE before IDAT");
png_ptr->mode |= PNG_HAVE_IDAT;
+ png_ptr->process_mode = PNG_READ_IDAT_MODE;
if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
if (png_ptr->push_length == 0)