Index: bytearray.ml
--- bytearray.ml.orig
+++ bytearray.ml
@@ -61,7 +61,9 @@ let of_string s =
 
 let mmap_of_string fd s =
   let l = String.length s in
-  let ba = Bigarray.Array1.map_file fd Bigarray.char Bigarray.c_layout true l in
+  let ba =
+    Bigarray.array1_of_genarray @@
+    Unix.map_file fd Bigarray.char Bigarray.c_layout true [|l|] in
   unsafe_blit_from_string s 0 ba 0 l;
   ba
 (*