diff --git a/pkgs/development/tools/misc/hydra/common.nix b/pkgs/development/tools/misc/hydra/common.nix
index c253bda36b8..a2d4aa2d754 100644
--- a/pkgs/development/tools/misc/hydra/common.nix
+++ b/pkgs/development/tools/misc/hydra/common.nix
@@ -5,7 +5,7 @@
 , docbook_xsl, openssh, gnused, coreutils, findutils, gzip, lzma, gnutar
 , rpm, dpkg, cdrkit, pixz, lib, boost, autoreconfHook, src ? null, version ? null
 , migration ? false, patches ? []
-, tests ? {}
+, tests ? {}, mdbook
 }:
 
 with stdenv;
@@ -84,7 +84,7 @@ in stdenv.mkDerivation rec {
       perlDeps perl nix
       postgresql # for running the tests
       nlohmann_json
-      boost
+      boost mdbook
     ];
 
   hydraPath = lib.makeBinPath (
diff --git a/pkgs/development/tools/misc/hydra/default.nix b/pkgs/development/tools/misc/hydra/default.nix
index 1636ad6dd71..a49f2231312 100644
--- a/pkgs/development/tools/misc/hydra/default.nix
+++ b/pkgs/development/tools/misc/hydra/default.nix
@@ -2,16 +2,13 @@
 
 {
   hydra-unstable = callPackage ./common.nix {
-    version = "2020-10-20";
+    version = "2021-03-10";
     src = fetchFromGitHub {
       owner = "NixOS";
       repo = "hydra";
-      rev = "79d34ed7c93af2daf32cf44ee0e3e0768f13f97c";
-      sha256 = "1lql899430137l6ghnhyz0ivkayy83fdr087ck2wq3gf1jv8pccj";
+      rev = "930f05c38eeac63ad6c3e3250de2667e2df2e96e";
+      sha256 = "06s2lg119p96i1j4rdbg3z097n25bgvq8ljdn4vcwcw3yz0lnswm";
     };
-    patches = [
-      ./hydra-nix-receiveContents.patch
-    ];
     nix = nixFlakes;
 
     tests = {
diff --git a/pkgs/development/tools/misc/hydra/hydra-nix-receiveContents.patch b/pkgs/development/tools/misc/hydra/hydra-nix-receiveContents.patch
deleted file mode 100644
index 61957e2190c..00000000000
--- a/pkgs/development/tools/misc/hydra/hydra-nix-receiveContents.patch
+++ /dev/null
@@ -1,18 +0,0 @@
-Update for https://github.com/NixOS/nix/commit/faa31f40
-
---- a/src/hydra-queue-runner/nar-extractor.cc
-+++ b/src/hydra-queue-runner/nar-extractor.cc
-@@ -48,9 +48,9 @@
--    void receiveContents(unsigned char * data, size_t len) override
-+    void receiveContents(std::string_view data) override
-     {
-         assert(expectedSize);
-         assert(curMember);
-         assert(hashSink);
--        *curMember->fileSize += len;
--        (*hashSink)(data, len);
-+        *curMember->fileSize += data.size();
-+        (*hashSink)(data);
-         if (curMember->contents) {
--            curMember->contents->append((char *) data, len);
-+            curMember->contents->append(data);
diff --git a/pkgs/tools/package-management/nix/default.nix b/pkgs/tools/package-management/nix/default.nix
index 9ab08007ec7..9c0beb224d2 100644
--- a/pkgs/tools/package-management/nix/default.nix
+++ b/pkgs/tools/package-management/nix/default.nix
@@ -13,7 +13,7 @@ common =
   , bash, coreutils, gzip, gnutar
   , pkg-config, boehmgc, perlPackages, libsodium, brotli, boost, editline, nlohmann_json
   , autoreconfHook, autoconf-archive, bison, flex
-  , jq, libarchive
+  , jq, libarchive, libcpuid
   , lowdown, mdbook
   # Used by tests
   , gmock
@@ -55,7 +55,7 @@ common =
         ]
         ++ lib.optionals stdenv.isDarwin [ Security ]
         ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium
-        ++ lib.optionals is24 [ libarchive gmock lowdown ]
+        ++ lib.optionals is24 [ libarchive gmock lowdown libcpuid ]
         ++ lib.optional withLibseccomp libseccomp
         ++ lib.optional withAWS
             ((aws-sdk-cpp.override {
@@ -212,28 +212,15 @@ in rec {
 
   nixUnstable = lib.lowPrio (callPackage common rec {
     name = "nix-2.4${suffix}";
-    suffix = "pre20201205_a5d85d0";
+    suffix = "pre20210308_1c0e3e4";
 
     src = fetchFromGitHub {
       owner = "NixOS";
       repo = "nix";
-      rev = "a5d85d07faa94cf3518e98273be4bee3d495f06a";
-      sha256 = "0g9jjhh0vs4hjrff5yx88x6sh7rk87ngvni3gnyxajqia957dipg";
+      rev = "1c0e3e453d41b869e4ac7e25dc1c00c349a7c411";
+      sha256 = "17killwp42d25f17yq2jida64j7d0ipz6zish78iqi450yrd9wrd";
     };
 
-    patches = [
-      (fetchpatch { # Fix build on gcc10
-        url = "https://github.com/NixOS/nix/commit/d4870462f8f539adeaa6dca476aff6f1f31e1981.patch";
-        sha256 = "mTvLvuxb2QVybRDgntKMq+b6da/s3YgM/ll2rWBeY/Y=";
-      })
-      # Fix the ETag bug. PR merged. Remove when updating to >= 20210125
-      # https://github.com/NixOS/nixpkgs/pull/109309#issuecomment-768331750
-      (fetchpatch {
-        url = "https://github.com/NixOS/nix/commit/c5b42c5a42138329c6d02da0d8a53cb59c6077f4.patch";
-        sha256 = "sha256-d4RNOKMxa4NMbFgYcqWRv2ByHt8F/XUWV+6P9qHz7S4=";
-      })
-    ];
-
     inherit storeDir stateDir confDir boehmgc;
   });