diff --git a/.github/workflows/Cabal-Linux-Remote.yml b/.github/workflows/Cabal-Linux-Remote.yml
index 88f9ef0..74bd2a9 100644
--- a/.github/workflows/Cabal-Linux-Remote.yml
+++ b/.github/workflows/Cabal-Linux-Remote.yml
@@ -26,13 +26,13 @@ jobs:
     steps:
 
       - name: "Git checkout"
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           submodules: recursive
 
       - name: "Haskell env setup"
         id: HaskEnvSetup
-        uses: haskell/actions/setup@v1
+        uses: haskell/actions/setup@v2
         with:
           ghc-version: ${{ matrix.ghc }}
 
@@ -44,7 +44,7 @@ jobs:
 
       # Still required for Remote
       - name: "Install Nix"
-        uses: cachix/install-nix-action@v16
+        uses: cachix/install-nix-action@v17
         if: matrix.packageRoot == 'hnix-store-remote'
 
       # Remote: Enabling testsuite, because it requires networking in the default Nix environment.
@@ -60,13 +60,14 @@ jobs:
         run: cp -a cabal.project.freeze ../cabal.project.freeze
 
       - name: "Configuring GitHub cache"
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: |
             ${{ steps.HaskEnvSetup.outputs.cabal-store }}
             dist-newstyle
           key: ${{ matrix.packageRoot }}-${{ runner.os }}-Cabal-${{ matrix.ghc }}-${{ hashFiles( 'cabal.project.freeze' ) }}
-          restore-keys: ${{ matrix.packageRoot }}-${{ runner.os }}-Cabal-${{ matrix.ghc }}-
+          # 2022-04-22: `v2-` added to invalidate corrupted caches, can be removed after one week
+          restore-keys: ${{ matrix.packageRoot }}-${{ runner.os }}-Cabal-${{ matrix.ghc }}-v2
 
       - name: "Build"
         run: cabal v2-build $cabalConfig
diff --git a/.github/workflows/Core-Cabal-Linux.yml b/.github/workflows/Core-Cabal-Linux.yml
index ba683f8..a7c0fd5 100644
--- a/.github/workflows/Core-Cabal-Linux.yml
+++ b/.github/workflows/Core-Cabal-Linux.yml
@@ -28,13 +28,13 @@ jobs:
     steps:
 
       - name: "Git checkout"
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           submodules: recursive
 
       - name: "Haskell env setup"
         id: HaskEnvSetup
-        uses: haskell/actions/setup@v1
+        uses: haskell/actions/setup@v2
         with:
           ghc-version: ${{ matrix.ghc }}
 
@@ -52,13 +52,14 @@ jobs:
         run: cp -a cabal.project.freeze ../cabal.project.freeze
 
       - name: "Configuring GitHub cache"
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: |
             ${{ steps.HaskEnvSetup.outputs.cabal-store }}
             dist-newstyle
           key: ${{ matrix.packageRoot }}-${{ runner.os }}-Cabal-${{ matrix.ghc }}-${{ hashFiles( 'cabal.project.freeze' ) }}
-          restore-keys: ${{ matrix.packageRoot }}-${{ runner.os }}-Cabal-${{ matrix.ghc }}-
+          # 2022-04-22: `v2-` added to invalidate corrupted caches, can be removed after one week
+          restore-keys: ${{ matrix.packageRoot }}-${{ runner.os }}-Cabal-${{ matrix.ghc }}-v2-
 
       - name: "Build"
         run: cabal v2-build $cabalConfig
diff --git a/.github/workflows/Core-Cabal-macOS.yml b/.github/workflows/Core-Cabal-macOS.yml
index 1116751..e6cde8e 100644
--- a/.github/workflows/Core-Cabal-macOS.yml
+++ b/.github/workflows/Core-Cabal-macOS.yml
@@ -25,13 +25,13 @@ jobs:
     steps:
 
       - name: "Git checkout"
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           submodules: recursive
 
       - name: "Haskell env setup"
         id: HaskEnvSetup
-        uses: haskell/actions/setup@v1
+        uses: haskell/actions/setup@v2
         with:
           ghc-version: '9.0'
 
@@ -49,7 +49,7 @@ jobs:
         run: cp -a cabal.project.freeze ../cabal.project.freeze
 
       - name: "Configuring GitHub cache"
-        uses: actions/cache@v2
+        uses: actions/cache@v3.0.1
         with:
           path: |
             ${{ steps.HaskEnvSetup.outputs.cabal-store }}
diff --git a/.github/workflows/On-Release-Cabal-Linux.yml b/.github/workflows/On-Release-Cabal-Linux.yml
index 800a934..dc3d388 100644
--- a/.github/workflows/On-Release-Cabal-Linux.yml
+++ b/.github/workflows/On-Release-Cabal-Linux.yml
@@ -25,13 +25,13 @@ jobs:
     steps:
 
       - name: "Git checkout"
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           submodules: recursive
 
       - name: "Haskell env setup"
         id: HaskEnvSetup
-        uses: haskell/actions/setup@v1
+        uses: haskell/actions/setup@v2
         with:
           ghc-version: ${{ matrix.ghc }}
 
@@ -43,7 +43,7 @@ jobs:
 
       # Still required for Remote
       - name: "Install Nix"
-        uses: cachix/install-nix-action@v16
+        uses: cachix/install-nix-action@v17
         if: matrix.packageRoot == 'hnix-store-remote'
 
       # Remote: Enabling testsuite, because it requires networking in the default Nix environment.
@@ -59,12 +59,13 @@ jobs:
         run: cp -a cabal.project.freeze ../cabal.project.freeze
 
       - name: "Configuring GitHub cache"
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: |
             ${{ steps.HaskEnvSetup.outputs.cabal-store }}
             dist-newstyle
           key: ${{ matrix.packageRoot }}-${{ runner.os }}-Cabal-${{ matrix.ghc }}-${{ hashFiles( 'cabal.project.freeze' ) }}
+          # 2022-04-22: `v2-` added to invalidate corrupted caches, can be removed after one week
           restore-keys: ${{ matrix.packageRoot }}-${{ runner.os }}-Cabal-${{ matrix.ghc }}-
 
       - name: "Build"
diff --git a/.github/workflows/Optional-Nix-dev-env-main.yml b/.github/workflows/Optional-Nix-dev-env-main.yml
index 8bc8beb..29bc7e4 100644
--- a/.github/workflows/Optional-Nix-dev-env-main.yml
+++ b/.github/workflows/Optional-Nix-dev-env-main.yml
@@ -28,11 +28,11 @@ jobs:
         working-directory: "./${{ matrix.packageRoot }}"
     steps:
     - name: "Git checkout"
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
       with:
         submodules: recursive
     - name: "Install Nix"
-      uses: cachix/install-nix-action@v16
+      uses: cachix/install-nix-action@v17
       with:
         nix_path: nixpkgs=channel:nixos-unstable
     - name: "Install Cachix"
@@ -42,9 +42,3 @@ jobs:
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
     - name: "Determined Nix-build"
       run: nix-build ../ -A "haskellPackages.${{ matrix.packageRoot }}"
-      env:
-        #  2020-12-22: NOTE: allowBroken ideally should be temporary.
-        NIXPKGS_ALLOW_BROKEN: "1"
-
-
-
diff --git a/default.nix b/default.nix
index da64968..d80828a 100644
--- a/default.nix
+++ b/default.nix
@@ -1,4 +1,14 @@
-{ pkgs ? import <nixpkgs> {} }: let
+{ rev ?  "c542baa0c894796c92a8173dead027f3b952c22e"
+, pkgs ?
+    if ((rev == "") || (rev == "default") || (rev == "local"))
+      then import <nixpkgs> {}
+      # Do not guard with hash, so the project is able to use current channels (rolling `rev`) of Nixpkgs
+      else import (builtins.fetchTarball "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz") {}
+    // {
+      # Try to build dependencies even if they are marked broken.
+      config.allowBroken = true;
+    }
+}: let
   overlay = import ./overlay.nix pkgs pkgs.haskell.lib;
   overrideHaskellPackages = orig: {
     buildHaskellPackages =
diff --git a/overlay.nix b/overlay.nix
index 819a40d..0687a6e 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -1,6 +1,6 @@
 pkgs: hlib: helf: huper: {
   hnix-store-remote =
-    ( helf.callCabal2nixWithOptions "hnix-store-remote" ./hnix-store-remote "-fio-testsuite" { relude = helf.relude_1_0_0_1; }
+    ( helf.callCabal2nixWithOptions "hnix-store-remote" ./hnix-store-remote "-fio-testsuite" { }
     ).overrideAttrs (attrs: {
         buildInputs = attrs.buildInputs ++ [
           pkgs.nix