diff --git a/vendors/ocplib-resto/lib_resto/resto.ml b/vendors/ocplib-resto/lib_resto/resto.ml
index 5b529634e..dfd0b64dc 100644
--- a/vendors/ocplib-resto/lib_resto/resto.ml
+++ b/vendors/ocplib-resto/lib_resto/resto.ml
@@ -265,6 +265,11 @@ module Path = struct
   let (/:) = add_arg
   let (/:*) = add_final_args
 
+  let subst0 = Internal.subst0
+  let subst1 = Internal.subst1
+  let subst2 = Internal.subst2
+  let subst3 = Internal.subst3
+
 end
 
 module Query = struct
diff --git a/vendors/ocplib-resto/lib_resto/resto.mli b/vendors/ocplib-resto/lib_resto/resto.mli
index 1364682a0..de0c8b91f 100644
--- a/vendors/ocplib-resto/lib_resto/resto.mli
+++ b/vendors/ocplib-resto/lib_resto/resto.mli
@@ -75,6 +75,15 @@ module Path : sig
   val prefix:
     ('prefix, 'a) path -> ('a, 'params) path -> ('prefix, 'params) path
 
+  val subst0:
+    ('p, 'p) path -> ('p2, 'p2) path
+  val subst1:
+    ('p, 'p * 'a) path -> ('p2, 'p2 * 'a) path
+  val subst2:
+    ('p, ('p * 'a) * 'b) path -> ('p2, ('p2 * 'a) * 'b) path
+  val subst3:
+    ('p, (('p * 'a) * 'b) * 'c) path -> ('p2, (('p2 * 'a) * 'b) * 'c) path
+
 end
 
 (** Service directory description *)