diff --git a/tests/bench/cross.nix b/tests/bench/cross.nix
index 338a7f1651..5b144d82fe 100644
--- a/tests/bench/cross.nix
+++ b/tests/bench/cross.nix
@@ -2,20 +2,20 @@
 
 let
   # pin Lean commit to avoid rebuilds
-  # 2020-03-04
-  lean = import (builtins.fetchGit { url = ../../.; rev = "21ca3709612ff7a05f0e5aa0849d776c1bc6d751"; }) {};
+  # 2020-08-18
+  lean = import (builtins.fetchGit { url = ../../.; rev = "d059d28c220247d51310c4ea437807c3446d36d7"; }) {};
   # for binarytrees.hs
   ghcPackages = p: [ p.parallel ];
-  ghc = pkgs.haskell.packages.ghc883.ghcWithPackages ghcPackages; #.override { withLLVM = true; };
-  ocaml = pkgs.ocaml-ng.ocamlPackages_latest.ocaml;
+  ghc = pkgs.haskell.packages.ghc884.ghcWithPackages ghcPackages; #.override { withLLVM = true; };
+  ocaml = pkgs.ocaml-ng.ocamlPackages_4_11.ocaml;
   # note that this will need to be compiled from source
   ocamlFlambda = ocaml.override { flambdaSupport = true; };
   mlton = pkgs.mlton;
   mlkit = pkgs.stdenv.mkDerivation {
     name = "mlkit";
-    src = pkgs.fetchzip {
-      url = "https://github.com/melsman/mlkit/releases/download/mlkit-4.4.2/mlkit_bin_dist.tgz";
-      sha256 = "079299h5m3gkk10qpn2r6va7kjj0sr9z3cs0knjz3qv1cldpzj7x";
+    src = builtins.fetchTarball {
+      url = "https://github.com/melsman/mlkit/releases/download/v4.5.0/mlkit_bin_dist.tgz";
+      sha256 = "1nrk2klhrr2xcm83y601w6dffl756qfk4kgvn3rkjlp7b2i8r8mr";
     };
     buildInputs = [ pkgs.makeWrapper ];
     dontBuild = true;
@@ -29,7 +29,7 @@ let
     '';
   };
   swift = pkgs.swift;
-  temci = import (builtins.fetchGit { url = http://github.com/parttimenerd/temci.git; rev = "ba1505a7c2de471a5821a2643b34de2d1c1af03e"; }) {};
+  temci = import (builtins.fetchGit { url = http://github.com/parttimenerd/temci.git; rev = "743a6ee9328fc8cb85d334dbce23a89d14cef4c5"; }) {};
 in pkgs.stdenv.mkDerivation rec {
   name = "bench";
   src = pkgs.lib.sourceFilesBySuffices ./. ["Makefile" "leanpkg.path" "temci.yaml" ".py" ".lean" ".hs" ".ml" ".sml"];
@@ -37,17 +37,17 @@ in pkgs.stdenv.mkDerivation rec {
   #LEAN_GCC_BIN = "${lean { stdenv = pkgs.gcc9Stdenv; }}/bin";
   LEAN_NO_REUSE_BIN = "${lean.overrideAttrs (attrs: {
     prePatch = ''
-      substituteInPlace src/Init/Lean/Compiler/IR.lean --replace "decls.map Decl.insertResetReuse" "decls"
-	  substituteInPlace src/shell/CMakeLists.txt --replace "install(TARGETS lean DESTINATION bin)" "install(PROGRAMS $<TARGET_FILE:lean_stage2> DESTINATION bin RENAME lean)"
+substituteInPlace src/Lean/Compiler/IR.lean --replace "decls.map Decl.insertResetReuse" "decls"
     '';
-	buildFlags = [ "lean_stage2" ];
+    buildFlags = [ "stage1.5" ];
+    installFlags = [ "-C stage1.5" ];
   })}/bin";
   LEAN_NO_BORROW_BIN = "${lean.overrideAttrs (attrs: {
     prePatch = ''
-      substituteInPlace src/Init/Lean/Compiler/IR.lean --replace "inferBorrow" "pure"
-	  substituteInPlace src/shell/CMakeLists.txt --replace "install(TARGETS lean DESTINATION bin)" "install(PROGRAMS $<TARGET_FILE:lean_stage2> DESTINATION bin RENAME lean)"
+substituteInPlace src/Lean/Compiler/IR.lean --replace "inferBorrow" "pure"
     '';
-	buildFlags = [ "lean_stage2" ];
+    buildFlags = [ "stage1.5" ];
+    installFlags = [ "-C stage1.5" ];
   })}/bin";
   LEAN_NO_ST_BIN = "${lean.overrideAttrs (attrs: { patches = [ ./disable-st.patch ]; })}/bin";
   PARSER_TEST_FILE = lean.src + "/src/Init/Core.lean";
diff --git a/tests/bench/disable-st.patch b/tests/bench/disable-st.patch
index 87f8a16f72..f0e46b26e9 100644
--- a/tests/bench/disable-st.patch
+++ b/tests/bench/disable-st.patch
@@ -4,13 +4,13 @@ Date: Mon, 11 Nov 2019 18:15:21 +0100
 Subject: [PATCH] disable ST objects
 
 ---
- src/runtime/lean.h | 6 +++---
+ src/include/lean/lean.h | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)
 
-diff --git a/src/runtime/lean.h b/src/runtime/lean.h
+diff --git a/src/include/lean/lean.h b/src/include/lean/lean.h
 index 6b37fd91a..c53137860 100644
---- a/src/runtime/lean.h
-+++ b/src/runtime/lean.h
+--- a/src/include/lean/lean.h
++++ b/src/include/lean/lean.h
 @@ -567,13 +567,13 @@ void lean_mark_persistent(lean_object * o);
 
  static inline void lean_set_st_header(lean_object * o, unsigned tag, unsigned other) {
diff --git a/tests/bench/nixpkgs.nix b/tests/bench/nixpkgs.nix
index 63ee6f49fc..213025cc52 100644
--- a/tests/bench/nixpkgs.nix
+++ b/tests/bench/nixpkgs.nix
@@ -1,5 +1,7 @@
 import (builtins.fetchTarball {
-  name = "nixpkgs-unstable-2020-03-04";
-  url = https://github.com/NixOS/nixpkgs/archive/d881de1e9641735ef3fd6beffb1a6006140baf17.tar.gz;
-  sha256 = "0mwgzjk0h7r7hv6mmaq54lw7wicwzp170z228h4j5yi5g2dz63kh";
+  name = "nixpkgs-unstable-2020-08-18";
+  # Commit hash from `git ls-remote https://github.com/NixOS/nixpkgs-channels nixpkgs-unstable`
+  url = https://github.com/nixos/nixpkgs/archive/c5815280e92112a25d958a2ec8b3704d7d90c506.tar.gz;
+  # Hash obtained using `nix-prefetch-url --unpack <url>`
+  sha256 = "09ic4s9s7w3lm0gmcxszm5j20cfv4n5lfvhdvgi7jzdbbbdps1nh";
 }) {}