diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 19bbff1ee..bb3025379 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -35,21 +35,16 @@ jobs:
             cpu: amd64
           - os: windows
             cpu: amd64
-        branch: [~, upstream/version-1-6, v2.0.6]
+        branch: [~, upstream/version-2-0]
         exclude:
           - target:
               os: macos
-            branch: upstream/version-1-6
+            branch: upstream/version-2-0
           - target:
               os: windows
-            branch: upstream/version-1-6
-          - target:
-              os: windows
-            branch: ~
+            branch: upstream/version-2-0
         include:
-          - branch: upstream/version-1-6
-            branch-short: version-1-6
-          - branch: v2.0.6
+          - branch: upstream/version-2-0
             branch-short: version-2-0
             nimflags-extra: --mm:refc
           - target:
diff --git a/nix/checksums.nix b/nix/checksums.nix
new file mode 100644
index 000000000..c3b322e3a
--- /dev/null
+++ b/nix/checksums.nix
@@ -0,0 +1,12 @@
+{ pkgs ? import <nixpkgs> { } }:
+
+let
+  tools = pkgs.callPackage ./tools.nix {};
+  sourceFile = ../vendor/nimbus-build-system/vendor/Nim/koch.nim;
+in pkgs.fetchFromGitHub {
+  owner = "nim-lang";
+  repo = "checksums";
+  rev = tools.findKeyValue "^ +ChecksumsStableCommit = \"([a-f0-9]+)\"$" sourceFile;
+  # WARNING: Requires manual updates when Nim compiler version changes.
+  hash = "sha256-AIiMBqLcGJCTkINHfJ2dN3ogitU7Za9Z9Sv9zjKeOQk=";
+}
diff --git a/nix/csources.nix b/nix/csources.nix
index ed217e5cf..33cd9d0fc 100644
--- a/nix/csources.nix
+++ b/nix/csources.nix
@@ -5,8 +5,8 @@ let
   sourceFile = ../vendor/nimbus-build-system/vendor/Nim/config/build_config.txt;
 in pkgs.fetchFromGitHub {
   owner = "nim-lang";
-  repo = "csources_v1";
+  repo = "csources_v2";
   rev = tools.findKeyValue "^nim_csourcesHash=([a-f0-9]+)$" sourceFile;
   # WARNING: Requires manual updates when Nim compiler version changes.
-  hash = "sha256-gwBFuR7lzO4zttR/6rgdjXMRxVhwKeLqDwpmOwMyU7A=";
+  hash = "sha256-UCLtoxOcGYjBdvHx7A47x6FjLMi6VZqpSs65MN7fpBs=";
 }
diff --git a/nix/default.nix b/nix/default.nix
index a86470974..a444329eb 100644
--- a/nix/default.nix
+++ b/nix/default.nix
@@ -19,9 +19,7 @@
 let
   inherit (pkgs) stdenv lib writeScriptBin callPackage;
 
-  nimble = callPackage ./nimble.nix {};
-  csources = callPackage ./csources.nix {};
-  revision = lib.substring 0 8 (src.rev or "dirty");
+  revision = lib.substring 0 8 (src.rev or "unknown");
 in stdenv.mkDerivation rec {
   pname = "nimbus-eth2";
   version = "${callPackage ./version.nix {}}-${revision}";
@@ -60,9 +58,10 @@ in stdenv.mkDerivation rec {
   preBuild = ''
     pushd vendor/nimbus-build-system/vendor/Nim
     mkdir dist
-    cp -r ${nimble} dist/nimble
-    cp -r ${csources} csources_v1
-    chmod 777 -R dist/nimble csources_v1
+    cp -r ${callPackage ./nimble.nix {}}    dist/nimble
+    cp -r ${callPackage ./checksums.nix {}} dist/checksums
+    cp -r ${callPackage ./csources.nix {}}  csources_v2
+    chmod 777 -R dist/nimble csources_v2
     sed -i 's/isGitRepo(destDir)/false/' tools/deps.nim
     popd
   '';
diff --git a/vendor/nimbus-build-system b/vendor/nimbus-build-system
index 8cdaec502..09a356878 160000
--- a/vendor/nimbus-build-system
+++ b/vendor/nimbus-build-system
@@ -1 +1 @@
-Subproject commit 8cdaec502b5a48f2514e11209f0d81a001d2a2b1
+Subproject commit 09a35687897041c152986f13473466fa55f987ca