diff --git a/libvips/foreign/vipspng.c b/libvips/foreign/vipspng.c
index df97a05b..7952383b 100644
--- a/libvips/foreign/vipspng.c
+++ b/libvips/foreign/vipspng.c
@@ -484,6 +484,11 @@ png2vips_interlace( Read *read, VipsImage *out )
 	for( y = 0; y < out->Ysize; y++ )
 		read->row_pointer[y] = VIPS_IMAGE_ADDR( out, 0, y );
 
+	/* Some libpng warn you to call png_set_interlace_handling(); here, but
+	 * that can actually break interlace. We have to live with the warning,
+	 * unfortunately.
+	 */
+
 	png_read_image( read->pPng, read->row_pointer );
 
 	png_read_end( read->pPng, NULL ); 
diff --git a/test/test_formats.sh b/test/test_formats.sh
index 52b075f7..abaa5241 100755
--- a/test/test_formats.sh
+++ b/test/test_formats.sh
@@ -196,8 +196,7 @@ if test_supported tiffload; then
 fi
 if test_supported pngload; then
 	test_format $image png 0
-# sadly broken in libpng 1.6.28 and 29
-#	test_format $image png 0 [compression=9,interlace=1]
+ 	test_format $image png 0 [compression=9,interlace=1]
 fi
 if test_supported jpegload; then
 	test_format $image jpg 90