diff --git a/.github/workflows/common.yml b/.github/workflows/common.yml
index f5d6e5930..d32659a68 100644
--- a/.github/workflows/common.yml
+++ b/.github/workflows/common.yml
@@ -87,7 +87,7 @@ jobs:
         uses: actions/checkout@v6
         with:
           repository: c-cube/qcheck
-          ref: v0.26
+          ref: v0.90
           path: multicoretests/qcheck
 
       - name: Pre-Setup
diff --git a/CHANGES.md b/CHANGES.md
index caaf52bfb..580207c7c 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -2,7 +2,8 @@
 
 ## NEXT RELEASE
 
-- ...
+- #578: Port libraries and test suite to qcheck-core.0.90,
+        incl. adjusting the `Lin.int_small` distribution to include negative numbers.
 
 ## 0.11
 
diff --git a/doc/example/stm_tests.ml b/doc/example/stm_tests.ml
index 104c05fd0..539d1377a 100644
--- a/doc/example/stm_tests.ml
+++ b/doc/example/stm_tests.ml
@@ -21,7 +21,7 @@ struct
     let char =
       if s=[]
       then Gen.printable
-      else Gen.(oneof [oneofl (List.map fst s); printable]) in
+      else Gen.(oneof [oneof_list (List.map fst s); printable]) in
     let int = Gen.nat in
     QCheck.make ~print:show_cmd
       (Gen.oneof
diff --git a/doc/paper-examples/stm_tests.ml b/doc/paper-examples/stm_tests.ml
index 73c1cd1f8..707cd59c4 100644
--- a/doc/paper-examples/stm_tests.ml
+++ b/doc/paper-examples/stm_tests.ml
@@ -23,7 +23,7 @@ struct
     let char =
       if s=[]
       then Gen.printable
-      else Gen.(oneof [oneofl (List.map fst s); printable]) in
+      else Gen.(oneof [oneof_list (List.map fst s); printable]) in
     let int = Gen.nat in
     QCheck.make ~print:show_cmd
       (Gen.oneof
diff --git a/doc/stm/mutable_set_v5.ml b/doc/stm/mutable_set_v5.ml
index 5b523a69b..65b4560e1 100644
--- a/doc/stm/mutable_set_v5.ml
+++ b/doc/stm/mutable_set_v5.ml
@@ -113,7 +113,7 @@ module Lib_spec : Spec = struct
     let gen =
       match state with
       | [] -> Gen.int
-      | xs -> Gen.(oneof [oneofl xs; int])
+      | xs -> Gen.(oneof [oneof_list xs; int])
     in
     QCheck.make ~print:show_cmd
       (QCheck.Gen.oneof
diff --git a/dune-project b/dune-project
index 4ce6e7140..7643327b0 100644
--- a/dune-project
+++ b/dune-project
@@ -18,7 +18,7 @@ the multicore run-time of OCaml 5.0.")
  (tags ("test" "test suite" "property" "qcheck" "quickcheck" "multicore" "non-determinism"))
  (depends
   base-domains
-  (qcheck-core          (>= "0.25"))
+  (qcheck-core          (>= "0.90"))
   (qcheck-lin           (= :version))
   (qcheck-stm           (= :version))))
 
@@ -32,7 +32,7 @@ sequential and parallel tests against a declarative model.")
  (depopts base-domains)
  (depends
   (ocaml (>= 4.12))
-  (qcheck-core           (>= "0.25"))
+  (qcheck-core           (>= "0.90"))
   (qcheck-multicoretests-util (= :version))))
 
 (package
@@ -47,7 +47,7 @@ and explained by some sequential interleaving.")
  (depopts base-domains)
  (depends
   (ocaml (>= 4.12))
-  (qcheck-core           (>= "0.25"))
+  (qcheck-core           (>= "0.90"))
   (qcheck-multicoretests-util (= :version))))
 
 (package
@@ -58,4 +58,4 @@ multicore programs.")
  (tags ("test" "property" "qcheck" "quickcheck" "multicore" "non-determinism"))
  (depends
   (ocaml (>= 4.12))
-  (qcheck-core           (>= "0.25"))))
+  (qcheck-core           (>= "0.90"))))
diff --git a/lib/lin.ml b/lib/lin.ml
index 3ac9a785f..6d7db1c23 100644
--- a/lib/lin.ml
+++ b/lib/lin.ml
@@ -157,7 +157,7 @@ let gen gen print = Gen (gen,print)
 let deconstructible print eq = Deconstr (print,eq)
 let gen_deconstructible gen print eq = GenDeconstr (gen,print,eq)
 
-let qcheck_nat64_small = QCheck.(map Int64.of_int small_nat)
+let qcheck_nat64_small = QCheck.(map Int64.of_int nat_small)
 
 (* QCheck's string shrinker reduces each char repeatedly which is too excessive for Lin *)
 let shrink_char c = QCheck.(if c = 'a' then Iter.empty else Iter.return 'a')
@@ -165,8 +165,9 @@ let shrink_string = QCheck.Shrink.string ~shrink:shrink_char
 let shrink_bytes = QCheck.Shrink.bytes ~shrink:shrink_char
 
 let string = QCheck.(set_shrink shrink_string string)
-let string_small = QCheck.(set_shrink shrink_string small_string)
-let string_small_printable = QCheck.(set_shrink shrink_string small_printable_string)
+let string_small = QCheck.(set_shrink shrink_string string_small)
+let string_small_printable = QCheck.(set_shrink shrink_string (string_size_of Gen.nat_small
+                                                                Gen.char_printable))
 
 let bytes = QCheck.(set_shrink shrink_bytes bytes)
 let bytes_small = QCheck.(set_shrink shrink_bytes bytes_small)
@@ -175,11 +176,11 @@ let bytes_small_printable = QCheck.(set_shrink shrink_bytes (bytes_small_of Gen.
 let unit =           GenDeconstr (QCheck.unit,           QCheck.Print.unit, (=))
 let bool =           GenDeconstr (QCheck.bool,           QCheck.Print.bool, (=))
 let char =           GenDeconstr (QCheck.char,           QCheck.Print.char, (=))
-let char_printable = GenDeconstr (QCheck.printable_char, QCheck.Print.char, (=))
-let nat_small =      GenDeconstr (QCheck.small_nat,      QCheck.Print.int,  (=))
+let char_printable = GenDeconstr (QCheck.char_printable, QCheck.Print.char, (=))
+let nat_small =      GenDeconstr (QCheck.nat_small,      QCheck.Print.int,  (=))
 let int =            GenDeconstr (QCheck.int,            QCheck.Print.int,  (=))
-let int_small =      GenDeconstr (QCheck.small_int,      QCheck.Print.int,  (=))
-let int_pos =        GenDeconstr (QCheck.pos_int,        QCheck.Print.int,  (=))
+let int_small =      GenDeconstr (QCheck.int_small,      QCheck.Print.int,  (=))
+let int_pos =        GenDeconstr (QCheck.int_pos,        QCheck.Print.int,  (=))
 let int_bound b =    GenDeconstr (QCheck.int_bound b,    QCheck.Print.int,  (=))
 let int32 =          GenDeconstr (QCheck.int32,          QCheck.Print.int32,   Int32.equal)
 let int64 =          GenDeconstr (QCheck.int64,          QCheck.Print.int64,   Int64.equal)
@@ -208,8 +209,8 @@ let list : type a c s. (a, c, s, combinable) ty -> (a list, c, s, combinable) ty
 
 let list_small : type a c s. (a, c, s, combinable) ty -> (a list, c, s, combinable) ty =
   fun ty -> match ty with
-    | Gen (arb, print) -> Gen (QCheck.small_list arb, QCheck.Print.list print)
-    | GenDeconstr (arb, print, eq) -> GenDeconstr (QCheck.small_list arb, QCheck.Print.list print, List.equal eq)
+    | Gen (arb, print) -> Gen (QCheck.list_small arb, QCheck.Print.list print)
+    | GenDeconstr (arb, print, eq) -> GenDeconstr (QCheck.list_small arb, QCheck.Print.list print, List.equal eq)
     | Deconstr (print, eq) -> Deconstr (QCheck.Print.list print, List.equal eq)
 
 let array : type a c s. (a, c, s, combinable) ty -> (a array, c, s, combinable) ty =
@@ -220,8 +221,8 @@ let array : type a c s. (a, c, s, combinable) ty -> (a array, c, s, combinable)
 
 let array_small : type a c s. (a, c, s, combinable) ty -> (a array, c, s, combinable) ty =
   fun ty -> match ty with
-    | Gen (arb, print) -> Gen (QCheck.array_of_size QCheck.Gen.small_nat arb, QCheck.Print.array print)
-    | GenDeconstr (arb, print, eq) -> GenDeconstr (QCheck.array_of_size QCheck.Gen.small_nat arb, QCheck.Print.array print, Array.for_all2 eq)
+    | Gen (arb, print) -> Gen (QCheck.array_small arb, QCheck.Print.array print)
+    | GenDeconstr (arb, print, eq) -> GenDeconstr (QCheck.array_small arb, QCheck.Print.array print, Array.for_all2 eq)
     | Deconstr (print, eq) -> Deconstr (QCheck.Print.array print, Array.for_all2 eq)
 
 let seq_iteri f s =
@@ -259,8 +260,8 @@ let seq : type a c s. (a, c, s, combinable) ty -> (a Seq.t, c, s, combinable) ty
 
 let seq_small : type a c s. (a, c, s, combinable) ty -> (a Seq.t, c, s, combinable) ty =
   fun ty -> match ty with
-    | Gen (arb, print) -> Gen (arb_seq QCheck.Gen.small_nat arb, print_seq print)
-    | GenDeconstr (arb, print, eq) -> GenDeconstr (arb_seq QCheck.Gen.small_nat arb, print_seq print, seq_equal eq)
+    | Gen (arb, print) -> Gen (arb_seq QCheck.Gen.nat_small arb, print_seq print)
+    | GenDeconstr (arb, print, eq) -> GenDeconstr (arb_seq QCheck.Gen.nat_small arb, print_seq print, seq_equal eq)
     | Deconstr (print, eq) -> Deconstr (print_seq print, seq_equal eq)
 
 let state = State
@@ -441,7 +442,7 @@ module MakeCmd (ApiSpec : Spec) : Internal.CmdSpec with type t = ApiSpec.t = str
          let shrink = gen_shrinker_of_desc fdesc in
          return (Cmd { name ; args ; rty ; print ; shrink ; f }))) ApiSpec.api
 
-  let gen_cmd : cmd QCheck.Gen.t = QCheck.Gen.frequency api
+  let gen_cmd : cmd QCheck.Gen.t = QCheck.Gen.oneof_weighted api
 
   let show_cmd (Cmd { args ; print ; _ }) = print args
 
diff --git a/lib/lin_effect.ml b/lib/lin_effect.ml
index 40c75680c..428ec17fa 100644
--- a/lib/lin_effect.ml
+++ b/lib/lin_effect.ml
@@ -52,7 +52,7 @@ module Make_internal (Spec : Internal.CmdSpec [@alert "-internal"]) = struct
       | UserCmd c  -> Spec.show_cmd c
 
     let gen_cmd =
-      (Gen.frequency
+      (Gen.oneof_weighted
          [(3,Gen.return SchedYield);
           (5,Gen.map (fun c -> UserCmd c) Spec.gen_cmd)])
 
diff --git a/multicoretests.opam b/multicoretests.opam
index 7554cfd42..ae6d53573 100644
--- a/multicoretests.opam
+++ b/multicoretests.opam
@@ -22,7 +22,7 @@ bug-reports: "https://github.com/ocaml-multicore/multicoretests/issues"
 depends: [
   "dune" {>= "3.18"}
   "base-domains"
-  "qcheck-core" {>= "0.25"}
+  "qcheck-core" {>= "0.90"}
   "qcheck-lin" {= version}
   "qcheck-stm" {= version}
   "odoc" {with-doc}
diff --git a/qcheck-lin.opam b/qcheck-lin.opam
index 44634612b..6cdcd7f4c 100644
--- a/qcheck-lin.opam
+++ b/qcheck-lin.opam
@@ -23,7 +23,7 @@ bug-reports: "https://github.com/ocaml-multicore/multicoretests/issues"
 depends: [
   "dune" {>= "3.18"}
   "ocaml" {>= "4.12"}
-  "qcheck-core" {>= "0.25"}
+  "qcheck-core" {>= "0.90"}
   "qcheck-multicoretests-util" {= version}
   "odoc" {with-doc}
 ]
diff --git a/qcheck-multicoretests-util.opam b/qcheck-multicoretests-util.opam
index 836a5401c..42f13bf0c 100644
--- a/qcheck-multicoretests-util.opam
+++ b/qcheck-multicoretests-util.opam
@@ -15,7 +15,7 @@ bug-reports: "https://github.com/ocaml-multicore/multicoretests/issues"
 depends: [
   "dune" {>= "3.18"}
   "ocaml" {>= "4.12"}
-  "qcheck-core" {>= "0.25"}
+  "qcheck-core" {>= "0.90"}
   "odoc" {with-doc}
 ]
 build: [
diff --git a/qcheck-stm.opam b/qcheck-stm.opam
index b8b4d4054..ffbff6ae0 100644
--- a/qcheck-stm.opam
+++ b/qcheck-stm.opam
@@ -23,7 +23,7 @@ bug-reports: "https://github.com/ocaml-multicore/multicoretests/issues"
 depends: [
   "dune" {>= "3.18"}
   "ocaml" {>= "4.12"}
-  "qcheck-core" {>= "0.25"}
+  "qcheck-core" {>= "0.90"}
   "qcheck-multicoretests-util" {= version}
   "odoc" {with-doc}
 ]
diff --git a/src/array/lin_internal_tests.ml b/src/array/lin_internal_tests.ml
index 6b992eeb2..5ab386feb 100644
--- a/src/array/lin_internal_tests.ml
+++ b/src/array/lin_internal_tests.ml
@@ -37,7 +37,7 @@ struct
 
   let gen_cmd =
     let open QCheck.Gen in
-    let int = small_nat and char = printable in
+    let int = nat_small and char = printable in
     oneof
       [
         pure Length;
diff --git a/src/array/stm_tests.ml b/src/array/stm_tests.ml
index 638cd0620..754b16b99 100644
--- a/src/array/stm_tests.ml
+++ b/src/array/stm_tests.ml
@@ -54,8 +54,8 @@ struct
   let power_of_2s = Array.init 63 (fun i -> 1 lsl i)
 
   let arb_cmd s =
-    let int_gen = Gen.(frequency [1,small_nat; 5,int_bound (List.length s - 1)]) in
-    let elem_gen = Gen.oneofa power_of_2s in
+    let int_gen = Gen.(oneof_weighted [1,nat_small; 5,int_bound (List.length s - 1)]) in
+    let elem_gen = Gen.oneof_array power_of_2s in
     QCheck.make ~print:show_cmd (*~shrink:shrink_cmd*)
       Gen.(oneof
              [ return Length;
diff --git a/src/bigarray/stm_tests.ml b/src/bigarray/stm_tests.ml
index c2f8bd2be..57e7e9c84 100644
--- a/src/bigarray/stm_tests.ml
+++ b/src/bigarray/stm_tests.ml
@@ -29,7 +29,7 @@ struct
   type sut   = (int, int_elt, c_layout) Array1.t
 
   let arb_cmd s =
-    let int_gen = Gen.(oneof [small_nat; int_bound (List.length s - 1)]) in
+    let int_gen = Gen.(oneof [nat_small; int_bound (List.length s - 1)]) in
     QCheck.make ~print:show_cmd (*~shrink:shrink_cmd*)
       Gen.(oneof
              [ return Size_in_bytes;
diff --git a/src/buffer/stm_tests.ml b/src/buffer/stm_tests.ml
index 44abe42ff..818db054f 100644
--- a/src/buffer/stm_tests.ml
+++ b/src/buffer/stm_tests.ml
@@ -47,7 +47,7 @@ struct
     | _ -> Iter.empty
 
   let arb_cmd s =
-    let int_gen,string_gen = Gen.(small_nat,small_string) in
+    let int_gen,string_gen = Gen.(nat_small,string_small) in
     QCheck.make ~print:show_cmd (*~shrink:shrink_cmd*)
       Gen.(oneof [return Contents;
                   return To_bytes;
diff --git a/src/bytes/stm_tests.ml b/src/bytes/stm_tests.ml
index 9f081b29d..eb1116ed6 100644
--- a/src/bytes/stm_tests.ml
+++ b/src/bytes/stm_tests.ml
@@ -50,7 +50,7 @@ struct
     | _ -> Iter.empty
 
   let arb_cmd s =
-    let int_gen = Gen.(oneof [small_nat; int_bound (List.length s - 1)]) in
+    let int_gen = Gen.(oneof [nat_small; int_bound (List.length s - 1)]) in
     let char_gen = Gen.printable in
     QCheck.make ~print:show_cmd ~shrink:shrink_cmd
       Gen.(oneof
diff --git a/src/domain/domain_spawntree.ml b/src/domain/domain_spawntree.ml
index c711d1cc9..df03c56f4 100644
--- a/src/domain/domain_spawntree.ml
+++ b/src/domain/domain_spawntree.ml
@@ -41,11 +41,11 @@ let gen max_height max_degree =
   let degree_gen = Gen.int_bound max_degree in
   Gen.sized_size height_gen @@ Gen.fix (fun rgen n ->
     match n with
-    | 0 -> Gen.oneofl [Incr;Decr]
+    | 0 -> Gen.oneof_list [Incr;Decr]
     | _ ->
       Gen.oneof
         [
-          Gen.oneofl [Incr;Decr];
+          Gen.oneof_list [Incr;Decr];
           Gen.map (fun ls -> Spawn ls) (Gen.list_size degree_gen (rgen (n-1)))
         ])
 
diff --git a/src/domain/stm_tests_dls.ml b/src/domain/stm_tests_dls.ml
index 46cc230d5..44270c328 100644
--- a/src/domain/stm_tests_dls.ml
+++ b/src/domain/stm_tests_dls.ml
@@ -26,7 +26,7 @@ struct
 
   let arb_cmd _s =
     let index = Gen.int_bound (length-1) in
-    let int_gen = Gen.small_nat in
+    let int_gen = Gen.nat_small in
     QCheck.make ~print:show_cmd
       Gen.(oneof
              [ map (fun i -> Get i) index;
diff --git a/src/dynarray/stm_tests.ml b/src/dynarray/stm_tests.ml
index c252e59a3..2e7fee529 100644
--- a/src/dynarray/stm_tests.ml
+++ b/src/dynarray/stm_tests.ml
@@ -184,14 +184,14 @@ module Dynarray_spec (Elem : Elem) = struct
     let open Gen in
     let arr_idx state = map (fun i -> I i) (int_bound (List.length state - 1)) in
     let elem = Elem.arb.gen in
-    let array elm_gen = Gen.array_size small_nat elm_gen in
-    let list elm_gen = Gen.list_size small_nat elm_gen in
+    let array elm_gen = Gen.array_small elm_gen in
+    let list elm_gen = Gen.list_small elm_gen in
     QCheck.make ~print:show_cmd ~shrink:shrink_cmd
-      (frequency
+      (oneof_weighted
         [ 5, return Create;
-          5, map2 (fun l x -> Make (l, x)) small_nat elem;
-          50, map2 (fun arr_idx elem_idx -> Get (arr_idx, elem_idx)) (arr_idx state) small_nat;
-          50, map3 (fun arr_idx elem_idx x -> Set (arr_idx, elem_idx, x)) (arr_idx state) small_nat elem;
+          5, map2 (fun l x -> Make (l, x)) nat_small elem;
+          50, map2 (fun arr_idx elem_idx -> Get (arr_idx, elem_idx)) (arr_idx state) nat_small;
+          50, map3 (fun arr_idx elem_idx x -> Set (arr_idx, elem_idx, x)) (arr_idx state) nat_small elem;
           50, map (fun i -> Is_empty i) (arr_idx state);
           50, map (fun i -> Length i) (arr_idx state);
           50, map (fun i -> Get_last i) (arr_idx state);
@@ -228,7 +228,7 @@ module Dynarray_spec (Elem : Elem) = struct
           50, map (fun i -> To_seq_rev_reentrant i) (arr_idx state);
           50, map (fun i -> Capacity i) (arr_idx state);
           50, map2 (fun i cap -> Ensure_capacity (i, cap)) (arr_idx state) nat;
-          50, map2 (fun i extra_cap -> Ensure_extra_capacity (i, extra_cap)) (arr_idx state) small_nat;
+          50, map2 (fun i extra_cap -> Ensure_extra_capacity (i, extra_cap)) (arr_idx state) nat_small;
           50, map (fun i -> Fit_capacity i) (arr_idx state);
           50, map2 (fun arr_i cap -> Set_capacity (arr_i, cap)) (arr_idx state) nat;
           33, map (fun arr_i -> Reset arr_i) (arr_idx state);
@@ -619,7 +619,7 @@ end
 
 module Int : Elem = struct
   type t = int
-  let arb = QCheck.small_int
+  let arb = QCheck.nat_small
   let pp = Format.pp_print_int
   let equal = Int.equal
   let show = snd STM.int
diff --git a/src/dynlink/lin_tests.ml b/src/dynlink/lin_tests.ml
index dd676f37f..74e195db3 100644
--- a/src/dynlink/lin_tests.ml
+++ b/src/dynlink/lin_tests.ml
@@ -5,7 +5,7 @@
 open Lin
 
 (* Two libraries that should exist, one that should not *)
-let library_name = QCheck.Gen.oneofl ["libA.cma"; "libB.cma"; "libC.cma"]
+let library_name = QCheck.Gen.oneof_list ["libA.cma"; "libB.cma"; "libC.cma"]
 let arb_library = QCheck.make library_name
 let print_library l = QCheck.Print.string (Dynlink.adapt_filename l)
 
diff --git a/src/ephemeron/stm_tests_spec.ml b/src/ephemeron/stm_tests_spec.ml
index 4e89c0812..1805d0116 100644
--- a/src/ephemeron/stm_tests_spec.ml
+++ b/src/ephemeron/stm_tests_spec.ml
@@ -86,11 +86,11 @@ let cleanup _ = ()
 let arb_cmd s =
   let key =
     if s = []
-    then Gen.(map Int64.of_int small_int)
-    else Gen.(oneof [oneofl (List.map fst s); map Int64.of_int small_int]) in
-  let data = Gen.(map Int64.of_int small_int) in
+    then Gen.(map Int64.of_int nat_small)
+    else Gen.(oneof [oneof_list (List.map fst s); map Int64.of_int nat_small]) in
+  let data = Gen.(map Int64.of_int nat_small) in
   QCheck.make ~print:show_cmd
-    Gen.(frequency
+    Gen.(oneof_weighted
            [ 1,return Clear;
              2,map2 (fun k v -> Add (k, v)) key data;
              2,map  (fun k -> Remove k) key;
diff --git a/src/floatarray/stm_tests.ml b/src/floatarray/stm_tests.ml
index 54ab257ba..ba13d7cdf 100644
--- a/src/floatarray/stm_tests.ml
+++ b/src/floatarray/stm_tests.ml
@@ -38,7 +38,7 @@ struct
   type sut = Float.Array.t
 
   let arb_cmd s =
-    let int_gen = Gen.(frequency [ (1,small_nat);
+    let int_gen = Gen.(oneof_weighted [ (1,nat_small);
                                    (7,int_bound (List.length s - 1)); ]) in
     let float_gen = Gen.float in
     QCheck.make ~print:show_cmd (*~shrink:shrink_cmd*)
diff --git a/src/gc/stm_tests_spec.ml b/src/gc/stm_tests_spec.ml
index 4bbbb697f..16939ffd6 100644
--- a/src/gc/stm_tests_spec.ml
+++ b/src/gc/stm_tests_spec.ml
@@ -163,7 +163,7 @@ let init_state =
 let array_length = 8
 
 let alloc_cmds =
-  let int_gen = Gen.small_nat in
+  let int_gen = Gen.nat_small in
   let str_len_gen = Gen.(map (fun shift -> 1 lsl (shift-1)) (int_bound 14)) in (*[-1;13] ~ [0;1;...4096;8196] *)
   let str_gen = Gen.map (fun l -> String.make l 'x') str_len_gen in
   let list_gen = Gen.map (fun l -> List.init l (fun _ -> 'l')) Gen.nat in
@@ -226,9 +226,9 @@ let gc_cmds =
    else [1,Gen.return Compact])
   @ alloc_cmds
 
-let arb_cmd _s = QCheck.make ~print:show_cmd (Gen.frequency gc_cmds)
+let arb_cmd _s = QCheck.make ~print:show_cmd (Gen.oneof_weighted gc_cmds)
 
-let arb_alloc_cmd _s = QCheck.make ~print:show_cmd (Gen.frequency alloc_cmds)
+let arb_alloc_cmd _s = QCheck.make ~print:show_cmd (Gen.oneof_weighted alloc_cmds)
 
 let next_state n s = match n with
   | Stat        -> s
diff --git a/src/hashtbl/stm_tests.ml b/src/hashtbl/stm_tests.ml
index 31747c4c3..cf44387e0 100644
--- a/src/hashtbl/stm_tests.ml
+++ b/src/hashtbl/stm_tests.ml
@@ -67,7 +67,7 @@ struct
     let char =
       if s=[]
       then Gen.printable
-      else Gen.(oneof [oneofl (List.map fst s); printable]) in
+      else Gen.(oneof [oneof_list (List.map fst s); printable]) in
     let int = Gen.nat in
     QCheck.make ~print:show_cmd
       (Gen.oneof
diff --git a/src/io/lin_internal_tests.ml b/src/io/lin_internal_tests.ml
index 09a3262ec..f55ffccbc 100644
--- a/src/io/lin_internal_tests.ml
+++ b/src/io/lin_internal_tests.ml
@@ -25,10 +25,10 @@ module In_channel_ops = struct
 
   let gen_cmd =
     let open QCheck.Gen in
-    frequency
+    oneof_weighted
       [1, return Close;
-       6, map (fun l -> Read l) small_nat;
-       6, map (fun l -> BlindRead l) small_nat;
+       6, map (fun l -> Read l) nat_small;
+       6, map (fun l -> BlindRead l) nat_small;
       ]
 
   let shrink_cmd _ = QCheck.Iter.empty
@@ -95,8 +95,8 @@ module Out_channel_ops = struct
 
   let gen_cmd =
     let open QCheck.Gen in
-    frequency
-      [10, map (fun i -> Seek (Int64.of_int i)) small_nat;
+    oneof_weighted
+      [10, map (fun i -> Seek (Int64.of_int i)) nat_small;
        10, return Close;
        10, return Flush;
        10, map (fun s -> Output_string s) string_small;
diff --git a/src/io/lin_tests_spec_io.ml b/src/io/lin_tests_spec_io.ml
index 6e023be38..ff604b4b5 100644
--- a/src/io/lin_tests_spec_io.ml
+++ b/src/io/lin_tests_spec_io.ml
@@ -31,7 +31,7 @@ module ICConf : Lin.Spec = struct
     let open QCheck in
     let zeroed_bytes n = Bytes.make n '\000' in
     let shrink b = Iter.map zeroed_bytes (Shrink.int (Bytes.length b))
-    and gen = Gen.map zeroed_bytes Gen.small_nat in
+    and gen = Gen.map zeroed_bytes Gen.nat_small in
     let bytes = make ~shrink ~small:Bytes.length ~print:Print.bytes gen in
     gen_deconstructible bytes (print Lin.bytes) Bytes.equal
 
diff --git a/src/io/stm_tests.ml b/src/io/stm_tests.ml
index a2545b95e..affea59d5 100644
--- a/src/io/stm_tests.ml
+++ b/src/io/stm_tests.ml
@@ -57,15 +57,15 @@ struct
                          binary_mode : bool; }
 
   let arb_cmd s =
-    let int64_gen = Gen.(map Int64.of_int small_int) in
+    let int64_gen = Gen.(map Int64.of_int nat_small) in
     let char_gen = Gen.printable in
-    let byte_gen = Gen.small_int in
-    let string_gen = Gen.small_string in
+    let byte_gen = Gen.nat_small in
+    let string_gen = Gen.string_small in
     let bytes_gen = Gen.bytes_small in
     QCheck.make ~print:show_cmd (*~shrink:shrink_cmd*)
       (match s with
        | Closed ->
-         Gen.(frequency [ (* generate only Open or Close cmds in Closed *)
+         Gen.(oneof_weighted [ (* generate only Open or Close cmds in Closed *)
              20,return Open_text;
              1,map (fun i -> Seek i) int64_gen;
              1,return Pos;
@@ -84,7 +84,7 @@ struct
              1,return Is_buffered;
            ])
        | Open _ ->
-         Gen.(frequency [
+         Gen.(oneof_weighted [
              (*1,return Open_text;*)
              3,map (fun i -> Seek i) int64_gen;
              3,return Pos;
diff --git a/src/lazy/lin_internal_tests.ml b/src/lazy/lin_internal_tests.ml
index 90da3ef93..bad73816a 100644
--- a/src/lazy/lin_internal_tests.ml
+++ b/src/lazy/lin_internal_tests.ml
@@ -54,7 +54,7 @@ struct
 
   let gen_cmd =
     let open QCheck.Gen in
-    let int_fun = (fun1 Observable.int QCheck.small_nat).gen in
+    let int_fun = (fun1 Observable.int QCheck.nat_small).gen in
     oneof
       [
         pure Force;
diff --git a/src/lazy/stm_tests.ml b/src/lazy/stm_tests.ml
index 8d86669f6..766346456 100644
--- a/src/lazy/stm_tests.ml
+++ b/src/lazy/stm_tests.ml
@@ -55,7 +55,7 @@ struct
   type sut = int Lazy.t
 
   let arb_cmd _s =
-    let int' = small_nat in
+    let int' = nat_small in
     QCheck.make ~print:show_cmd
       (Gen.oneof
          [Gen.return Force;
diff --git a/src/neg_tests/stm_tests_clist_spec.ml b/src/neg_tests/stm_tests_clist_spec.ml
index e6089e3c4..c61b35f47 100644
--- a/src/neg_tests/stm_tests_clist_spec.ml
+++ b/src/neg_tests/stm_tests_clist_spec.ml
@@ -33,7 +33,7 @@ struct
     let mem_gen =
       if s=[]
       then int_gen
-      else Gen.oneof [int_gen; Gen.oneofl s]
+      else Gen.oneof [int_gen; Gen.oneof_list s]
     in
     QCheck.make ~print:show_cmd
       (Gen.oneof
diff --git a/src/queue/lin_internal_tests.ml b/src/queue/lin_internal_tests.ml
index 56d722e0c..6226e99c4 100644
--- a/src/queue/lin_internal_tests.ml
+++ b/src/queue/lin_internal_tests.ml
@@ -36,7 +36,7 @@ module Spec =
     let gen_cmd =
       let open QCheck.Gen in
       let int = nat
-      and fct = (fun2 Observable.int Observable.int QCheck.small_int).gen in
+      and fct = (fun2 Observable.int Observable.int QCheck.nat_small).gen in
       oneof
         [
           map (fun x -> Add x) int;
diff --git a/src/semaphore/stm_tests_binary.ml b/src/semaphore/stm_tests_binary.ml
index a4a45e499..81d632cb8 100644
--- a/src/semaphore/stm_tests_binary.ml
+++ b/src/semaphore/stm_tests_binary.ml
@@ -38,7 +38,7 @@ module SBConf =
     let arb_cmd s =
       let cmds = [ Release; TryAcquire; ] in
       let cmds = if s = 1 then Acquire :: cmds else cmds in
-      QCheck.make ~print:show_cmd (Gen.oneofl cmds)
+      QCheck.make ~print:show_cmd (Gen.oneof_list cmds)
 
     let next_state c s = match c with
       | Release -> 1
diff --git a/src/semaphore/stm_tests_counting.ml b/src/semaphore/stm_tests_counting.ml
index efee0356e..85b85bbeb 100644
--- a/src/semaphore/stm_tests_counting.ml
+++ b/src/semaphore/stm_tests_counting.ml
@@ -44,7 +44,7 @@ module SCConf =
     let arb_cmd s =
       let cmds = [ Release; TryAcquire; GetValue ] in
       let cmds = if s > 0 then Acquire :: cmds else cmds in
-      QCheck.make ~print:show_cmd (Gen.oneofl cmds)
+      QCheck.make ~print:show_cmd (Gen.oneof_list cmds)
 
     let next_state c s = match c with
       | Release -> s+1
@@ -79,7 +79,7 @@ module SCTest_dom = STM_domain.Make(struct
     let arb_cmd s =
       let cmds = [ Release; TryAcquire; ] in (* No GetValue *)
       let cmds = if s > 0 then Acquire :: cmds else cmds in
-      QCheck.make ~print:show_cmd (Gen.oneofl cmds)
+      QCheck.make ~print:show_cmd (Gen.oneof_list cmds)
   end)
 
 let _ =
diff --git a/src/stack/lin_internal_tests.ml b/src/stack/lin_internal_tests.ml
index 6f3fb55ad..382269788 100644
--- a/src/stack/lin_internal_tests.ml
+++ b/src/stack/lin_internal_tests.ml
@@ -36,7 +36,7 @@ module Spec =
     let gen_cmd =
       let open QCheck.Gen in
       let int = nat
-      and fct = (fun2 Observable.int Observable.int QCheck.small_int).gen in
+      and fct = (fun2 Observable.int Observable.int QCheck.nat_small).gen in
       oneof
         [
           map (fun x -> Push x) int;
diff --git a/src/sys/stm_tests.ml b/src/sys/stm_tests.ml
index 72ae3b807..76f0a698d 100644
--- a/src/sys/stm_tests.ml
+++ b/src/sys/stm_tests.ml
@@ -45,7 +45,7 @@ struct
     | Directory d ->
       (match Map_names.bindings d.fs_map with
       | [] -> Gen.return []
-      | bindings -> Gen.(oneofl bindings >>= fun (n, sub_fs) ->
+      | bindings -> Gen.(oneof_list bindings >>= fun (n, sub_fs) ->
         Gen.oneof [
           Gen.return [n];
           Gen.map (fun l -> n::l) (gen_existing_path sub_fs)]
@@ -59,7 +59,7 @@ struct
       (match Map_names.bindings d.fs_map with
       | [] -> Gen.return None
       | bindings ->
-        Gen.(oneofl bindings >>= fun (n, sub_fs) ->
+        Gen.(oneof_list bindings >>= fun (n, sub_fs) ->
              oneof [
                return (Some ([],n));
                map (function None -> Some ([],n)
@@ -67,7 +67,7 @@ struct
             )
       )
 
-  let name_gen = Gen.oneofl ["aaa" ; "bbb" ; "ccc" ; "ddd" ; "eee"]
+  let name_gen = Gen.oneof_list ["aaa" ; "bbb" ; "ccc" ; "ddd" ; "eee"]
   let path_gen s = Gen.(oneof [gen_existing_path s; list_size (int_bound 5) name_gen]) (* can be empty *)
   let pair_gen s =
     let fresh_pair_gen = Gen.(pair (list_size (int_bound 5) name_gen)) name_gen in
diff --git a/src/thread/thread_createtree.ml b/src/thread/thread_createtree.ml
index bd3fe216d..60e2765d4 100644
--- a/src/thread/thread_createtree.ml
+++ b/src/thread/thread_createtree.ml
@@ -41,11 +41,11 @@ let gen max_height max_degree =
   let degree_gen = Gen.int_bound max_degree in
   Gen.sized_size height_gen @@ Gen.fix (fun rgen n ->
     match n with
-    | 0 -> Gen.oneofl [Incr;Decr]
+    | 0 -> Gen.oneof_list [Incr;Decr]
     | _ ->
       Gen.oneof
         [
-          Gen.oneofl [Incr;Decr];
+          Gen.oneof_list [Incr;Decr];
           Gen.map (fun ls -> Create ls) (Gen.list_size degree_gen (rgen (n-1)))
         ])
 
diff --git a/src/thread/thread_joingraph.ml b/src/thread/thread_joingraph.ml
index 50b6e85df..af61aecfc 100644
--- a/src/thread/thread_joingraph.ml
+++ b/src/thread/thread_joingraph.ml
@@ -143,7 +143,7 @@ let build_dep_graph test_input =
 
 let test_arb_work ~thread_bound =
   Test.make ~name:"Thread.create/join" ~count:100
-    (arb_deps (Gen.frequencyl [(10,Atomic_incr);
+    (arb_deps (Gen.oneof_list_weighted [(10,Atomic_incr);
                                (10,Tak);
                                (1,Gc_minor)]) thread_bound)
     (fun test_input ->
diff --git a/src/threadomain/threadomain.ml b/src/threadomain/threadomain.ml
index bb154e4e5..fc2d08ea0 100644
--- a/src/threadomain/threadomain.ml
+++ b/src/threadomain/threadomain.ml
@@ -4,7 +4,7 @@ open QCheck2
    domain or a thread *)
 
 (** Generate a permutation of [0..sz-1] *)
-let permutation sz = Gen.shuffle_a (Array.init sz (fun x -> x))
+let permutation sz = Gen.shuffle_array (Array.init sz (fun x -> x))
 
 (** Generate a tree of size nodes
  The tree is represented as an array [a] of integers, [a.(i)] being
@@ -97,7 +97,7 @@ let gen_spawn_join sz =
   let open Gen in
   build_spawn_join sz
     <$> tree sz <*> permutation sz <*> tree sz
-    <*> array_size (pure sz) (frequencyl [(4, false); (1, true)])
+    <*> array_size (pure sz) (oneof_list_weighted [(4, false); (1, true)])
     <*> array_size (pure sz) worktype
 
 type handle =
diff --git a/src/weak/stm_tests_hashset_spec.ml b/src/weak/stm_tests_hashset_spec.ml
index 90a1f0b57..655cd6c9b 100644
--- a/src/weak/stm_tests_hashset_spec.ml
+++ b/src/weak/stm_tests_hashset_spec.ml
@@ -58,9 +58,9 @@ let arb_cmd s =
   let string_gen = Gen.(string_small_of printable) in
   let data_gen = match s with
     | [] -> string_gen
-    | _::_ -> Gen.(oneof [oneofl s; string_gen]) in
+    | _::_ -> Gen.(oneof [oneof_list s; string_gen]) in
   QCheck.make ~print:show_cmd (*~shrink:shrink_cmd*)
-    Gen.(frequency
+    Gen.(oneof_weighted
            [ 1,return Clear;
              2,map (fun d -> Merge d) data_gen;
              2,map (fun d -> Add d) data_gen;
diff --git a/src/weak/stm_tests_weak_spec.ml b/src/weak/stm_tests_weak_spec.ml
index 755526fbe..8c81a7433 100644
--- a/src/weak/stm_tests_weak_spec.ml
+++ b/src/weak/stm_tests_weak_spec.ml
@@ -40,10 +40,10 @@ let _shrink_cmd c = match c with
           map (fun j -> Fill (i,j,d_opt)) (Shrink.int j))
 
 let arb_cmd s =
-  let int_gen = Gen.(oneof [small_nat; int_bound (List.length s - 1)]) in
+  let int_gen = Gen.(oneof [nat_small; int_bound (List.length s - 1)]) in
   let data_gen = Gen.(string_small_of printable) in
   QCheck.make ~print:show_cmd (*~shrink:shrink_cmd*)
-    Gen.(frequency
+    Gen.(oneof_weighted
            [ 1,return Length;
              1,map2 (fun i d_opt -> Set (i,d_opt)) int_gen (option data_gen);
              2,map (fun i -> Get i) int_gen;
diff --git a/test/mutable_set_v5.ml b/test/mutable_set_v5.ml
index 16512417c..64ec4f1d7 100644
--- a/test/mutable_set_v5.ml
+++ b/test/mutable_set_v5.ml
@@ -119,7 +119,7 @@ module Lib_spec : Spec = struct
     let gen =
       match state with
       | [] -> Gen.int
-      | xs -> Gen.(oneof [oneofl xs; int])
+      | xs -> Gen.(oneof [oneof_list xs; int])
     in
     QCheck.make ~print:show_cmd
       (QCheck.Gen.oneof