--- sexplib-7.0.5.old/myocamlbuild.ml	2017-11-17 17:21:13.878934029 +0000
+++ sexplib-7.0.5/myocamlbuild.ml	2017-11-17 17:30:04.133960027 +0000
@@ -269,8 +269,8 @@
           (* by using Before_options one let command line options have an higher priority *)
           (* on the contrary using After_options will guarantee to have the higher priority *)
           (* override default commands by ocamlfind ones *)
-          Options.ocamlc     := ocamlfind & A"ocamlc";
-          Options.ocamlopt   := ocamlfind & A"ocamlopt";
+          Options.ocamlc     := ocamlfind & S[A"ocamlc"; A"-unsafe-string"];
+          Options.ocamlopt   := ocamlfind & S[A"ocamlopt"; A"-unsafe-string"];
           Options.ocamldep   := ocamlfind & A"ocamldep";
           Options.ocamldoc   := ocamlfind & A"ocamldoc";
           Options.ocamlmktop := ocamlfind & A"ocamlmktop"