diff -ur ocaml-gettext-0.3.7.old/libgettext-ocaml/gettextMo_int32.ml ocaml-gettext-0.3.7/libgettext-ocaml/gettextMo_int32.ml
--- ocaml-gettext-0.3.7.old/libgettext-ocaml/gettextMo_int32.ml	2017-03-01 22:03:24.000000000 +0000
+++ ocaml-gettext-0.3.7/libgettext-ocaml/gettextMo_int32.ml	2017-11-08 18:33:04.486280040 +0000
@@ -104,11 +104,11 @@
      (Int32.to_int length,Int32.to_int offset)
    in
    if 0 <= ioffset + ilength && ioffset + ilength < in_channel_length chn then
-     let str = String.make ilength 'X'
+     let str = Bytes.make ilength 'X'
      in
      seek_in chn ioffset;
      really_input chn str 0 ilength;
-     str
+     Bytes.to_string str
    else
      (* We use this exception, because that what should happen if we try to 
         read the string *)