diff --git a/frama_Clang_option.ml b/frama_Clang_option.ml
index fbb96a41fc382a68b2b77a3d45d0a74afd1463f6..9bf1edfa935d092d7290b16dbcbea3fd527d8149 100644
--- a/frama_Clang_option.ml
+++ b/frama_Clang_option.ml
@@ -34,7 +34,7 @@ module Clang_command =
     struct
       let option_name = "-cxx-clang-command"
       let default = "framaCIRGen"
-      let help = 
+      let help =
         "use <cmd> as the parsing command. Defaults to " ^ default
       let arg_name = "cmd"
     end)
@@ -153,20 +153,22 @@ let parseable_output_hook _ f =
 
 let () = ParseableOutput.add_set_hook parseable_output_hook
 
-module C_std_headers = 
+module C_std_headers =
   String(
     struct
-      let default = (Fc_config.datadir:>string) ^ "/libc"
+      let default =
+        (Kernel.Share.get_dir "libc" :> string)
       let option_name = "-cxx-cstdlib-path"
       let help = "<path> where to look for C standard headers \
                   (default: Frama-C libc in " ^ default ^ ")"
       let arg_name = "path"
     end)
 
-module Cxx_std_headers = 
+module Cxx_std_headers =
   String(
     struct
-      let default = (Fc_config.datadir:>string) ^ "/frama-clang/libc++"
+      let default =
+        (Kernel.Share.get_dir "frama-clang/libc++" :> string)
       let option_name = "-cxx-c++stdlib-path"
       let help = "<path> where to look for C++ standard headers \
                   (default: FClang libc++ in " ^ default ^ ")"