diff --git a/third_party/nixpkgs/default.nix b/third_party/nixpkgs/default.nix
index 3911a2522..fdbd619cf 100644
--- a/third_party/nixpkgs/default.nix
+++ b/third_party/nixpkgs/default.nix
@@ -13,16 +13,16 @@ let
   # nixos-unstable, and the current stable channel of the latest NixOS
   # release.
 
-  # Tracking nixos-unstable as of 2021-05-25.
+  # Tracking nixpkgs-unstable as of 2021-06-05.
   unstableHashes = {
-    commit = "900115a4f7fdd9189e7803ca781a65be663f2c89";
-    sha256 = "11551nawxjbgya8sq1p6ghkbws9qz9fbfq3wqawm3zh8ayr4l13j";
+    commit = "2a1c29ef4bacac06f9b677931027bf053952618c";
+    sha256 = "1gxkvp4bf222v23kpb7di8iay5gl2qyv5qwgmb10nzdr87avbcax";
   };
 
-  # Tracking nixos-20.09 as of 2021-05-25.
+  # Tracking nixos-21.05 as of 2021-06-02.
   stableHashes = {
-    commit = "ac60476ed94fd5424d9f3410c438825f793a8cbb";
-    sha256 = "1dlvpdsy5v09c7rj5f7xgakyj722yqr4415davjpcmrk4n5kw76v";
+    commit = "eaba7870ffc3400eca4407baa24184b7fe337ec1";
+    sha256 = "115disiz4b08iw46cidc7lm0advrxn5g2ldmlrxd53zf03skyb2w";
   };
 
   # import the nixos-unstable package set, or optionally use the
@@ -47,9 +47,7 @@ let
   # Overlay for packages that should come from the stable channel
   # instead (e.g. because something is broken in unstable).
   stableOverlay = self: super: {
-    inherit (stableNixpkgs)
-      awscli # TODO(grfn): Move back to unstable once it is fixed
-      ;
+    # nothing picked from stable currently
   };
 in import nixpkgsSrc {
   config.allowUnfree = true;
diff --git a/third_party/overlays/haskell/default.nix b/third_party/overlays/haskell/default.nix
index 45681194a..d6a178a1e 100644
--- a/third_party/overlays/haskell/default.nix
+++ b/third_party/overlays/haskell/default.nix
@@ -10,16 +10,6 @@ let
   overrides = hsSelf: hsSuper: with super.haskell.lib; rec {
     generic-arbitrary = appendPatch hsSuper.generic-arbitrary
       [ ./patches/generic-arbitrary-export-garbitrary.patch ];
-
-    # check dependencies cause circular dependency on itself
-    # and thus an infinite recursion
-    random = dontCheck hsSuper.random_1_2_0;
-
-    # random <1.2
-    test-framework = doJailbreak hsSuper.test-framework;
-    hashable = doJailbreak hsSuper.hashable;
-    test-framework-quickcheck2 = doJailbreak hsSuper.test-framework-quickcheck2;
-    pandoc = doJailbreak hsSuper.pandoc;
   };
 in {
   haskellPackages = super.haskellPackages.override {
diff --git a/users/grfn/system/home/modules/development.nix b/users/grfn/system/home/modules/development.nix
index a79f5b987..6ad44abf0 100644
--- a/users/grfn/system/home/modules/development.nix
+++ b/users/grfn/system/home/modules/development.nix
@@ -76,7 +76,9 @@ with lib;
 
     nodePackages.prettier
   ] ++ optionals (stdenv.isLinux) [
-    julia-stable
+    # TODO(grfn): replace with stable again once the current julia debacle
+    # is resolved upstream, see https://github.com/NixOS/nixpkgs/pull/121114
+    julia_16-bin
     valgrind
   ];
 
diff --git a/users/grfn/system/system/iso.nix b/users/grfn/system/system/iso.nix
index 256aee6a5..4adccebfb 100644
--- a/users/grfn/system/system/iso.nix
+++ b/users/grfn/system/system/iso.nix
@@ -3,7 +3,7 @@
 let
   configuration = { ... }: {
     imports = [
-      "${pkgs.path}/nixos/modules/installer/cd-dvd/installation-cd-minimal-new-kernel.nix"
+      "${pkgs.path}/nixos/modules/installer/cd-dvd/installation-cd-minimal.nix"
       "${pkgs.path}/nixos/modules/installer/cd-dvd/channel.nix"
     ];
 
diff --git a/users/tazjin/nixos/tverskoy/default.nix b/users/tazjin/nixos/tverskoy/default.nix
index f6b85b39d..ef1dc1853 100644
--- a/users/tazjin/nixos/tverskoy/default.nix
+++ b/users/tazjin/nixos/tverskoy/default.nix
@@ -45,6 +45,7 @@ in lib.fix(self: {
     kernelPackages = pkgs.linuxPackages_latest;
     loader.systemd-boot.enable = true;
     loader.efi.canTouchEfiVariables = true;
+    zfs.enableUnstable = true;
   };
 
   fileSystems = {