diff --git a/pkgs/tools/package-management/nix/common.nix b/pkgs/tools/package-management/nix/common.nix
index d0840d206b67..19080e22ed3d 100644
--- a/pkgs/tools/package-management/nix/common.nix
+++ b/pkgs/tools/package-management/nix/common.nix
@@ -42,6 +42,7 @@ in
 , docbook5
 , editline
 , flex
+, git
 , gnutar
 , gtest
 , gzip
@@ -54,6 +55,7 @@ in
 , libxml2
 , libxslt
 , lowdown
+, man
 , mdbook
 , mdbook-linkcheck
 , nlohmann_json
@@ -142,6 +144,11 @@ self = stdenv.mkDerivation {
     aws-sdk-cpp
   ];
 
+  installCheckInputs = lib.optionals atLeast221 [
+    git
+    man
+  ];
+
   propagatedBuildInputs = [
     boehmgc
   ] ++ lib.optionals (atLeast27) [
diff --git a/pkgs/tools/package-management/nix/default.nix b/pkgs/tools/package-management/nix/default.nix
index 92c988ea5d08..f5f2b81f6532 100644
--- a/pkgs/tools/package-management/nix/default.nix
+++ b/pkgs/tools/package-management/nix/default.nix
@@ -263,6 +263,11 @@ in lib.makeExtensible (self: ({
     hash = "sha256-bfFe38BkoQws7om4gBtBWoNTLkt9piMXdLLoHYl+vBQ=";
   };
 
+  nix_2_21 = common {
+    version = "2.21.0";
+    hash = "sha256-9b9qJ+7rGjLKbIswMf0/2pgUWH/xOlYLk7P4WYNcGDs=";
+  };
+
   # The minimum Nix version supported by Nixpkgs
   # Note that some functionality *might* have been backported into this Nix version,
   # making this package an inaccurate representation of what features are available
@@ -282,7 +287,7 @@ in lib.makeExtensible (self: ({
 
   stable = addFallbackPathsCheck self.nix_2_18;
 
-  unstable = self.nix_2_20;
+  unstable = self.nix_2_21;
 } // lib.optionalAttrs config.allowAliases {
   nix_2_4 = throw "nixVersions.nix_2_4 has been removed";