diff --git a/direnvrc b/direnvrc
index 8f2c38f..7e6b6ba 100644
--- a/direnvrc
+++ b/direnvrc
@@ -38,7 +38,7 @@ _nix() {
 
 _require_version() {
   local cmd=$1 version=$2 required=$3
-  if ! printf "%s\n" "$required" "$version" | sort --check=quiet --version-sort; then
+  if ! printf "%s\n" "$required" "$version" | LC_ALL=C sort -c -V 2>/dev/null; then
     _nix_direnv_fatal \
       "minimum required $(basename "$cmd") version is $required (installed: $version)"
   fi
diff --git a/flake.nix b/flake.nix
index 0f5175c..6f21c32 100644
--- a/flake.nix
+++ b/flake.nix
@@ -19,7 +19,10 @@
   outputs = inputs @ { flake-parts, ... }:
     flake-parts.lib.mkFlake { inherit inputs; }
       ({ lib, ... }: {
-        imports = [ ./treefmt.nix ];
+        imports = [
+          ./treefmt.nix
+          ./pkgs/bash4/flake-module.nix
+        ];
         systems = [
           "aarch64-linux"
           "x86_64-linux"
@@ -37,21 +40,6 @@
             test-runner-unstable = pkgs.callPackage ./test-runner.nix {
               nixVersion = "unstable";
             };
-            bash4 = pkgs.bash.overrideAttrs (_old: {
-              name = "bash-4.4";
-              src = pkgs.fetchurl {
-                url = "https://ftp.gnu.org/gnu/bash/bash-4.4.tar.gz";
-                hash = "sha256-2GszksEgLo/1pCOzAuYoTbf49DXqnzm1sbIP06w238s=";
-              };
-              patches = [ ];
-            });
-            direnv-bash4 = pkgs.direnv.override {
-              bash = config.packages.bash4;
-            };
-            test-runner-bash4 = pkgs.callPackage ./test-runner.nix {
-              nixVersion = "stable";
-              direnv = config.packages.direnv-bash4;
-            };
           };
 
           devShells.default = pkgs.callPackage ./shell.nix {
diff --git a/pkgs/bash4/bash-4.4-patches.nix b/pkgs/bash4/bash-4.4-patches.nix
new file mode 100644
index 0000000..ad39940
--- /dev/null
+++ b/pkgs/bash4/bash-4.4-patches.nix
@@ -0,0 +1,27 @@
+# Automatically generated by `update-patch-set.sh'; do not edit.
+
+patch: [
+  (patch "001" "03vzy7qwjdd5qvl3ydg99naazas2qmyd0yhnrflgjbbm64axja1y")
+  (patch "002" "0lrwq6vyqism3yqv9s7kzaf3dsl4q5w9r5svcqz279qp7qca083h")
+  (patch "003" "1chqww2rj6g42b8s60q5zlzy0jzp684jkpsbrbfy1vzxja8mmpsi")
+  (patch "004" "1cy8abf96hkrjhw921ndr0shlcnc52bg45rn6xri4v5clhq0l25d")
+  (patch "005" "0a8515kyk4zsgmvlqvlganjfr7pq0j6kzpr4d6xx02kpbdr4n7i2")
+  (patch "006" "1f24wgqngmj2mrj9yibwvc2zvlmn5xi53mnw777g3l40c4m2x3ka")
+  (patch "007" "1bzdsnqaf05gdbqpsixhan8vygjxpcxlz1dd8d9f5jdznw3wq76y")
+  (patch "008" "1firw915mjm03hbbw9a70ch3cpgrgnvqjpllgdnn6csr8q04f546")
+  (patch "009" "0g1l56kvw61rpw7dqa9fcl9llkl693h73g631hrhxlm030ddssqb")
+  (patch "010" "01lfhrkdsdkdz8ypzapr614ras23x7ckjnr60aa5bzkaqprccrc4")
+  (patch "011" "038p7mhnq9m65g505hi3827jkf9f35nd1cy00w8mwafpyxp44mnx")
+  (patch "012" "0gh6lbb1rwpk44pvbamm6vzdfi50xnwkqd9v7s8cjwk3pz973hps")
+  (patch "013" "1djkx0w9v62q78gz3jsvamj1jq53i6hbfrfhhsw86ihwpjnfy98v")
+  (patch "014" "0z5ikcq9zyxw79d0z36r5p0mspnb5piavbv03jmlan1wnknmrxx7")
+  (patch "015" "09n307fi1j257abhm295k6ksmnzw47ka2zhnr0i5lbdnpvn04xnk")
+  (patch "016" "1cgi1y6mifm8hsgv4avj5ih76535js3qba1sqwbfvp7si76927sh")
+  (patch "017" "0w6jpj2giakji1ir83rpkx1y7n7xqppah3j748m6dm38hywr0gvp")
+  (patch "018" "1k58h4wxbsg7r4rwhrvzx5hfbapba2nxjysbhh6qp6ki5ys99i2v")
+  (patch "019" "07n1i5610lbs672x1s8g82qn3qfj06s0ip3z80sri0g8vxp0s5r7")
+  (patch "020" "0b2jk5n1af1vh590qfc52hv65mafb4vl1xv26s8j5a3byb5y4h0q")
+  (patch "021" "1hblcd2xmqqlp0idnavw66570n7m0yv5rbbr873c2gkn982mk3xx")
+  (patch "022" "0yfbjzr79vzjs2hyi5m8iy2b38fq7vikdfa4zqdvjsp36q4iycs5")
+  (patch "023" "1dlism6qdx60nvzj0v7ndr7lfahl4a8zmzckp13hqgdx7xpj7v2g")
+]
diff --git a/pkgs/bash4/default.nix b/pkgs/bash4/default.nix
new file mode 100644
index 0000000..a3376e9
--- /dev/null
+++ b/pkgs/bash4/default.nix
@@ -0,0 +1,15 @@
+{ bash, fetchurl }:
+
+bash.overrideAttrs (_old: {
+  name = "bash-4.4";
+  src = fetchurl {
+    url = "https://ftp.gnu.org/gnu/bash/bash-4.4.tar.gz";
+    hash = "sha256-2GszksEgLo/1pCOzAuYoTbf49DXqnzm1sbIP06w238s=";
+  };
+
+  # generated with update-patch-set.sh from nixpkgs/pkgs/shells/bash
+  patches = import ./bash-4.4-patches.nix (nr: sha256: fetchurl {
+    url = "mirror://gnu/bash/bash-4.4-patches/bash44-${nr}";
+    inherit sha256;
+  });
+})
diff --git a/pkgs/bash4/flake-module.nix b/pkgs/bash4/flake-module.nix
new file mode 100644
index 0000000..3d3683e
--- /dev/null
+++ b/pkgs/bash4/flake-module.nix
@@ -0,0 +1,13 @@
+{ self, withSystem, ... }: {
+  flake.packages.x86_64-linux = withSystem "x86_64-linux"
+    ({ pkgs, ... }: {
+      bash4 = pkgs.callPackage ./. { };
+      direnv-bash4 = pkgs.direnv.override {
+        bash = self.packages.x86_64-linux.bash4;
+      };
+      test-runner-bash4 = pkgs.callPackage ../../test-runner.nix {
+        nixVersion = "stable";
+        direnv = self.packages.x86_64-linux.direnv-bash4;
+      };
+    });
+}