Index: cairo-ocaml-1.2.0/src/cairo_png.ml
===================================================================
--- cairo-ocaml-1.2.0.orig/src/cairo_png.ml
+++ cairo-ocaml-1.2.0/src/cairo_png.ml
@@ -7,13 +7,13 @@
 (**************************************************************************)
 
 external image_surface_create_from_stream_unsafe : 
-  (string -> int -> unit) -> Cairo.image_surface = "ml_cairo_image_surface_create_from_png_stream_unsafe"
+  (bytes -> int -> unit) -> Cairo.image_surface = "ml_cairo_image_surface_create_from_png_stream_unsafe"
 
 let image_surface_create_from_channel ic =
   image_surface_create_from_stream_unsafe
     (fun s n ->
       for i = 0 to n - 1 do
-	String.unsafe_set s i (input_char ic)
+	Bytes.unsafe_set s i (input_char ic)
       done)
 
 let image_surface_create_from_file fname =