diff --git a/src/plugins/wp/Why3Provers.ml b/src/plugins/wp/Why3Provers.ml
index 60e196d6d4909d84e459ac13dd54c85c1a6031c0..38a9e97129761c0fae3e4dae9a1904f9c1e6b3be 100644
--- a/src/plugins/wp/Why3Provers.ml
+++ b/src/plugins/wp/Why3Provers.ml
@@ -26,7 +26,8 @@
 
 let cfg = lazy
   begin
-    try Why3.Whyconf.init_config None
+    let extra_config = Wp_parameters.Why3ExtraConfig.get () in
+    try Why3.Whyconf.init_config ~extra_config None
     with exn ->
       Wp_parameters.abort "%a" Why3.Exn_printer.exn_printer exn
   end
diff --git a/src/plugins/wp/wp_parameters.ml b/src/plugins/wp/wp_parameters.ml
index 5a63447c8844bb2ea82f7bdb07887248f54d53e8..23ff0dda57c622e47b57170e242faee62c225069 100644
--- a/src/plugins/wp/wp_parameters.ml
+++ b/src/plugins/wp/wp_parameters.ml
@@ -983,6 +983,16 @@ module Why3Flags =
       let help = "Additional options for Why3"
     end)
 
+let () = Parameter_customize.set_group wp_prover_options
+let () = Parameter_customize.no_category ()
+module Why3ExtraConfig =
+  String_list
+    (struct
+      let option_name = "-wp-why3-extra-config"
+      let arg_name = "file,..."
+      let help = "Additional config files for Why3"
+    end)
+
 (* ------------------------------------------------------------------------ *)
 (* --- PO Management                                                    --- *)
 (* ------------------------------------------------------------------------ *)
diff --git a/src/plugins/wp/wp_parameters.mli b/src/plugins/wp/wp_parameters.mli
index 74e6e0376c6e09feb6272c801f8ad3d73d887be1..786bf2d170668267ba39a507a078806ac18793de 100644
--- a/src/plugins/wp/wp_parameters.mli
+++ b/src/plugins/wp/wp_parameters.mli
@@ -136,6 +136,7 @@ module Steps: Parameter_sig.Int
 module Procs: Parameter_sig.Int
 module ProofTrace: Parameter_sig.Bool
 module Why3Flags: Parameter_sig.String_list
+module Why3ExtraConfig: Parameter_sig.String_list
 
 module Auto: Parameter_sig.String_list
 module AutoDepth: Parameter_sig.Int