diff --git a/gen.opam b/gen.opam
index c335a8a..1a63fda 100644
--- a/gen.opam
+++ b/gen.opam
@@ -10,7 +10,7 @@ build: [
   ["dune" "build" "@doc" "-p" name] {with-doc}
 ]
 depends: [
-  "dune" {build}
+  "dune" {>= "1.1"}
   "base-bytes"
   "odoc" {with-doc}
   "qcheck" {with-test}
diff --git a/src/dune b/src/dune
index 5ef28aa..1e7b505 100644
--- a/src/dune
+++ b/src/dune
@@ -1,19 +1,26 @@
+(executable
+ (name mkshims)
+ (modules mkshims)
+ (libraries dune.configurator))
+
+(rule
+ (targets GenShims_.ml)
+ (deps ./mkshims.exe)
+ (action (run ./mkshims.exe)))
+
 (rule
   (targets flambda.flags)
   (deps (file mkflags.ml))
   (mode fallback)
-  (action
-    (run ocaml ./mkflags.ml))
-  )
+  (action (run ocaml ./mkflags.ml)))
 
 (library
   (name gen)
   (public_name gen)
   (wrapped false)
-  (modules Gen GenLabels GenM GenClone GenMList GenM_intf Gen_intf GenLabels_intf)
-  (flags :standard -w +a-4-42-44-48-50-58-32-60@8 -safe-string -nolabels)
+  (modules Gen GenLabels GenM GenClone GenMList GenM_intf Gen_intf GenLabels_intf GenShims_)
+  (flags :standard -warn-error -a+8 -safe-string -nolabels)
   (ocamlopt_flags :standard (:include flambda.flags))
   (libraries bytes)
-  (inline_tests (backend qtest.lib))
-  )
+  (inline_tests (backend qtest.lib)))
 
diff --git a/src/gen.ml b/src/gen.ml
index 2540fd6..e823d5a 100644
--- a/src/gen.ml
+++ b/src/gen.ml
@@ -376,7 +376,7 @@ let take n gen =
 
 (*$Q
   (Q.pair Q.small_int (Q.list Q.small_int)) (fun (n,l) -> \
-    of_list l |> take n |> length = Pervasives.min n (List.length l))
+    of_list l |> take n |> length = GenShims_.Stdlib.min n (List.length l))
 *)
 
 (* call [gen] at most [n] times, and stop *)
@@ -668,7 +668,7 @@ let eq ?(eq=(=)) gen1 gen2 =
     eq (of_list l1)(of_list l2) = (l1 = l2))
 *)
 
-let lexico ?(cmp=Pervasives.compare) gen1 gen2 =
+let lexico ?(cmp=GenShims_.Stdlib.compare) gen1 gen2 =
   let rec lexico () =
     match gen1(), gen2() with
     | None, None -> 0
@@ -684,7 +684,7 @@ let compare ?cmp gen1 gen2 = lexico ?cmp gen1 gen2
 (*$Q
   (Q.pair (Q.list Q.small_int)(Q.list Q.small_int)) (fun (l1,l2) -> \
     let sign x = if x < 0 then -1 else if x=0 then 0 else 1 in \
-    sign (compare (of_list l1)(of_list l2)) = sign (Pervasives.compare l1 l2))
+    sign (compare (of_list l1)(of_list l2)) = sign (GenShims_.Stdlib.compare l1 l2))
 *)
 
 let rec find p e = match e () with
@@ -838,17 +838,17 @@ let merge next_gen =
 
 (*$T
   merge (of_list [of_list [1;3;5]; of_list [2;4;6]; of_list [7;8;9]]) \
-    |> to_list |> List.sort Pervasives.compare = [1;2;3;4;5;6;7;8;9]
+    |> to_list |> List.sort GenShims_.Stdlib.compare = [1;2;3;4;5;6;7;8;9]
 *)
 
 (*$R
   let e = of_list [1--3; 4--6; 7--9] in
   let e' = merge e in
   OUnit.assert_equal [1;2;3;4;5;6;7;8;9]
-    (to_list e' |> List.sort Pervasives.compare);
+    (to_list e' |> List.sort GenShims_.Stdlib.compare);
 *)
 
-let intersection ?(cmp=Pervasives.compare) gen1 gen2 =
+let intersection ?(cmp=GenShims_.Stdlib.compare) gen1 gen2 =
   let x1 = ref (gen1 ()) in
   let x2 = ref (gen2 ()) in
   let rec next () =
@@ -869,7 +869,7 @@ let intersection ?(cmp=Pervasives.compare) gen1 gen2 =
     |> to_list = [1;2;4;8]
 *)
 
-let sorted_merge ?(cmp=Pervasives.compare) gen1 gen2 =
+let sorted_merge ?(cmp=GenShims_.Stdlib.compare) gen1 gen2 =
   let x1 = ref (gen1 ()) in
   let x2 = ref (gen2 ()) in
   fun () ->
@@ -937,7 +937,7 @@ module Heap = struct
         x
 end
 
-let sorted_merge_n ?(cmp=Pervasives.compare) l =
+let sorted_merge_n ?(cmp=GenShims_.Stdlib.compare) l =
   (* make a heap of (value, generator) *)
   let cmp (v1,_) (v2,_) = cmp v1 v2 in
   let heap = Heap.empty ~cmp in
@@ -1169,7 +1169,7 @@ let product gena genb =
 
 (*$T
   product (1--3) (of_list ["a"; "b"]) |> to_list \
-    |> List.sort Pervasives.compare = \
+    |> List.sort GenShims_.Stdlib.compare = \
       [1, "a"; 1, "b"; 2, "a"; 2, "b"; 3, "a"; 3, "b"]
 *)
 
@@ -1177,7 +1177,7 @@ let product gena genb =
   let printer = pi2list in
   let e = Gen.product (1--3) (4--5) in
   OUnit.assert_equal ~printer [1,4; 1,5; 2,4; 2,5; 3,4; 3,5]
-    (List.sort Pervasives.compare (Gen.to_list e));
+    (List.sort GenShims_.Stdlib.compare (Gen.to_list e));
 *)
 
 (* Group equal consecutive elements together. *)
@@ -1232,7 +1232,7 @@ let uniq ?(eq=(=)) gen =
     [0;1;0;2;3;4;5;10]
 *)
 
-let sort ?(cmp=Pervasives.compare) gen =
+let sort ?(cmp=GenShims_.Stdlib.compare) gen =
   (* build heap *)
   let h = Heap.empty ~cmp in
   iter (Heap.insert h) gen;
@@ -1248,7 +1248,7 @@ let sort ?(cmp=Pervasives.compare) gen =
 
 (* NOTE: using a set is not really possible, because once we have built the
    set there is no simple way to iterate on it *)
-let sort_uniq ?(cmp=Pervasives.compare) gen =
+let sort_uniq ?(cmp=GenShims_.Stdlib.compare) gen =
   uniq ~eq:(fun x y -> cmp x y = 0) (sort ~cmp gen)
 
 (*$T
@@ -1350,7 +1350,7 @@ let permutations g =
   next (make_machine (List.length l) l)
 
 (*$T permutations
-  permutations (1--3) |> to_list |> List.sort Pervasives.compare = \
+  permutations (1--3) |> to_list |> List.sort GenShims_.Stdlib.compare = \
     [[1;2;3]; [1;3;2]; [2;1;3]; [2;3;1]; [3;1;2]; [3;2;1]]
   permutations empty |> to_list = [[]]
   permutations (singleton 1) |> to_list = [[1]]
@@ -1434,7 +1434,7 @@ let permutations_heap g =
   else next {elts = a; n=n; is=[0]}
 
 (*$T permutations_heap
-  permutations_heap (1--3) |> to_list |> List.sort Pervasives.compare = \
+  permutations_heap (1--3) |> to_list |> List.sort GenShims_.Stdlib.compare = \
     [[|1;2;3|]; [|1;3;2|]; [|2;1;3|]; [|2;3;1|]; [|3;1;2|]; [|3;2;1|]]
   permutations_heap empty |> to_list = []
   permutations_heap (singleton 1) |> to_list = [[|1|]]
@@ -1480,8 +1480,8 @@ let combinations n g =
   next (make_state n l)
 
 (*$T
-  combinations 2 (1--4) |> map (List.sort Pervasives.compare) \
-    |> to_list |> List.sort Pervasives.compare = \
+  combinations 2 (1--4) |> map (List.sort GenShims_.Stdlib.compare) \
+    |> to_list |> List.sort GenShims_.Stdlib.compare = \
     [[1;2]; [1;3]; [1;4]; [2;3]; [2;4]; [3;4]]
   combinations 0 (1--4) |> to_list = [[]]
   combinations 1 (singleton 1) |> to_list = [[1]]
@@ -1521,12 +1521,12 @@ let power_set g =
   next (make_state l)
 
 (*$T
-  power_set (1--3) |> map (List.sort Pervasives.compare) \
-    |> to_list |> List.sort Pervasives.compare = \
+  power_set (1--3) |> map (List.sort GenShims_.Stdlib.compare) \
+    |> to_list |> List.sort GenShims_.Stdlib.compare = \
     [[]; [1]; [1;2]; [1;2;3]; [1;3]; [2]; [2;3]; [3]]
   power_set empty |> to_list = [[]]
-  power_set (singleton 1) |> map (List.sort Pervasives.compare) \
-    |> to_list |> List.sort Pervasives.compare = [[]; [1]]
+  power_set (singleton 1) |> map (List.sort GenShims_.Stdlib.compare) \
+    |> to_list |> List.sort GenShims_.Stdlib.compare = [[]; [1]]
 *)
 
 (** {3 Conversion} *)
@@ -1843,10 +1843,10 @@ module Restart = struct
 
   let uniq ?eq e () = uniq ?eq (e ())
 
-  let sort ?(cmp=Pervasives.compare) enum =
+  let sort ?(cmp=GenShims_.Stdlib.compare) enum =
     fun () -> sort ~cmp (enum ())
 
-  let sort_uniq ?(cmp=Pervasives.compare) e =
+  let sort_uniq ?(cmp=GenShims_.Stdlib.compare) e =
     let e' = sort ~cmp e in
     uniq ~eq:(fun x y -> cmp x y = 0) e'
 
diff --git a/src/genClone.ml b/src/genClone.ml
index 7c3fc50..4538bf4 100644
--- a/src/genClone.ml
+++ b/src/genClone.ml
@@ -7,6 +7,7 @@ type 'a gen = unit -> 'a option
 
 class virtual ['a] t = object
   method virtual gen : 'a gen  (** Generator of values tied to this copy *)
+
   method virtual clone : 'a t  (** Clone the internal state *)
 end
 (** A generator that can be cloned as many times as required. *)
diff --git a/src/mkshims.ml b/src/mkshims.ml
new file mode 100644
index 0000000..05d5bf9
--- /dev/null
+++ b/src/mkshims.ml
@@ -0,0 +1,16 @@
+module C = Configurator.V1
+
+let write_file f s =
+  let out = open_out f in
+  output_string out s; flush out; close_out out
+
+let shims_pre_407 = "module Stdlib = Pervasives"
+
+let shims_post_407 = "module Stdlib = Stdlib"
+
+let () =
+  C.main ~name:"mkshims" (fun c ->
+    let version = C.ocaml_config_var_exn c "version" in
+    let major, minor = Scanf.sscanf version "%u.%u" (fun maj min -> maj, min) in
+    write_file "GenShims_.ml" (if (major, minor) >= (4,7) then shims_post_407 else shims_pre_407);
+    )