diff --git a/libvips/foreign/pngsave.c b/libvips/foreign/pngsave.c
index 3ebbb2ef..1979a7a8 100644
--- a/libvips/foreign/pngsave.c
+++ b/libvips/foreign/pngsave.c
@@ -206,7 +206,7 @@ vips_foreign_save_png_buffer_build( VipsObject *object )
 
 	area = vips_area_new_blob( (VipsCallbackFn) vips_free, obuf, olen );
 
-	g_object_set( object, "buf", area, NULL );
+	g_object_set( object, "buffer", area, NULL );
 
 	return( 0 );
 }