diff --git a/flake.nix b/flake.nix
index 5cc269c..6ab820e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,19 +4,30 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-utils.url = "github:numtide/flake-utils";
+    flake-compat = {
+      url = "github:edolstra/flake-compat";
+      flake = false;
+    };
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs = { self, nixpkgs, flake-utils, ... }:
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = import nixpkgs {
           inherit system;
           overlays = [
-            (final: prev: rec {
-              jre = prev.adoptopenjdk-hotspot-bin-11;
-              jdk = jre;
-            })
+            (self: super:
+              let jvm = super.jdk11_headless;
+              in {
+                jre = jvm;
+                jdk = jvm;
+              })
           ];
         };
-      in { devShell = import ./shell.nix { inherit pkgs; }; });
+      in {
+        devShell = with pkgs;
+          mkShell {
+            buildInputs = [ jre ammonite coursier bloop sbt scalafmt ];
+          };
+      });
 }

diff --git a/flake.nix b/flake.nix
index 5cc269c..6ab820e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,19 +4,30 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-utils.url = "github:numtide/flake-utils";
+    flake-compat = {
+      url = "github:edolstra/flake-compat";
+      flake = false;
+    };
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs = { self, nixpkgs, flake-utils, ... }:
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = import nixpkgs {
           inherit system;
           overlays = [
-            (final: prev: rec {
-              jre = prev.adoptopenjdk-hotspot-bin-11;
-              jdk = jre;
-            })
+            (self: super:
+              let jvm = super.jdk11_headless;
+              in {
+                jre = jvm;
+                jdk = jvm;
+              })
           ];
         };
-      in { devShell = import ./shell.nix { inherit pkgs; }; });
+      in {
+        devShell = with pkgs;
+          mkShell {
+            buildInputs = [ jre ammonite coursier bloop sbt scalafmt ];
+          };
+      });
 }
diff --git a/shell.nix b/shell.nix
index bc59c53..fa2a56c 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,11 +1,6 @@
-{ pkgs ? import <nixpkgs> {
-  overlays = [
-    (final: prev: rec {
-      jre = prev.adoptopenjdk-hotspot-bin-11;
-      jdk = jre;
-    })
-  ];
-} }:
-
-with pkgs;
-mkShell { buildInputs = [ jre ammonite coursier bloop sbt scalafmt ]; }
+(import (let lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+in fetchTarball {
+  url =
+    "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+  sha256 = lock.nodes.flake-compat.locked.narHash;
+}) { src = ./.; }).shellNix

diff --git a/flake.nix b/flake.nix
index 5cc269c..6ab820e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,19 +4,30 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-utils.url = "github:numtide/flake-utils";
+    flake-compat = {
+      url = "github:edolstra/flake-compat";
+      flake = false;
+    };
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs = { self, nixpkgs, flake-utils, ... }:
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = import nixpkgs {
           inherit system;
           overlays = [
-            (final: prev: rec {
-              jre = prev.adoptopenjdk-hotspot-bin-11;
-              jdk = jre;
-            })
+            (self: super:
+              let jvm = super.jdk11_headless;
+              in {
+                jre = jvm;
+                jdk = jvm;
+              })
           ];
         };
-      in { devShell = import ./shell.nix { inherit pkgs; }; });
+      in {
+        devShell = with pkgs;
+          mkShell {
+            buildInputs = [ jre ammonite coursier bloop sbt scalafmt ];
+          };
+      });
 }
diff --git a/shell.nix b/shell.nix
index bc59c53..fa2a56c 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,11 +1,6 @@
-{ pkgs ? import <nixpkgs> {
-  overlays = [
-    (final: prev: rec {
-      jre = prev.adoptopenjdk-hotspot-bin-11;
-      jdk = jre;
-    })
-  ];
-} }:
-
-with pkgs;
-mkShell { buildInputs = [ jre ammonite coursier bloop sbt scalafmt ]; }
+(import (let lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+in fetchTarball {
+  url =
+    "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+  sha256 = lock.nodes.flake-compat.locked.narHash;
+}) { src = ./.; }).shellNix
diff --git a/src/main/g8/flake.nix b/src/main/g8/flake.nix
index 469660f..d965203 100644
--- a/src/main/g8/flake.nix
+++ b/src/main/g8/flake.nix
@@ -1,5 +1,5 @@
 {
-  description = "Posuzovani shody";
+  description = "IW project";
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
@@ -12,11 +12,17 @@
         pkgs = import nixpkgs {
           inherit system;
           overlays = [
-            (final: prev: rec {
-              jre = prev.jdk$java_version$_headless;
-              jdk = jre;
-            })
+            (self: super:
+              let jvm = super.jdk$java_version$_headless;
+              in {
+                jre = jvm;
+                jdk = jvm;
+              })
           ];
         };
-      in { devShell = import ./shell.nix { inherit pkgs; }; });
+      in { devShell = with pkgs;
+          mkShell {
+            buildInputs = [ jre ammonite coursier bloop sbt scalafmt ];
+          };
+      });
 }

diff --git a/flake.nix b/flake.nix
index 5cc269c..6ab820e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,19 +4,30 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-utils.url = "github:numtide/flake-utils";
+    flake-compat = {
+      url = "github:edolstra/flake-compat";
+      flake = false;
+    };
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs = { self, nixpkgs, flake-utils, ... }:
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = import nixpkgs {
           inherit system;
           overlays = [
-            (final: prev: rec {
-              jre = prev.adoptopenjdk-hotspot-bin-11;
-              jdk = jre;
-            })
+            (self: super:
+              let jvm = super.jdk11_headless;
+              in {
+                jre = jvm;
+                jdk = jvm;
+              })
           ];
         };
-      in { devShell = import ./shell.nix { inherit pkgs; }; });
+      in {
+        devShell = with pkgs;
+          mkShell {
+            buildInputs = [ jre ammonite coursier bloop sbt scalafmt ];
+          };
+      });
 }
diff --git a/shell.nix b/shell.nix
index bc59c53..fa2a56c 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,11 +1,6 @@
-{ pkgs ? import <nixpkgs> {
-  overlays = [
-    (final: prev: rec {
-      jre = prev.adoptopenjdk-hotspot-bin-11;
-      jdk = jre;
-    })
-  ];
-} }:
-
-with pkgs;
-mkShell { buildInputs = [ jre ammonite coursier bloop sbt scalafmt ]; }
+(import (let lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+in fetchTarball {
+  url =
+    "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+  sha256 = lock.nodes.flake-compat.locked.narHash;
+}) { src = ./.; }).shellNix
diff --git a/src/main/g8/flake.nix b/src/main/g8/flake.nix
index 469660f..d965203 100644
--- a/src/main/g8/flake.nix
+++ b/src/main/g8/flake.nix
@@ -1,5 +1,5 @@
 {
-  description = "Posuzovani shody";
+  description = "IW project";
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
@@ -12,11 +12,17 @@
         pkgs = import nixpkgs {
           inherit system;
           overlays = [
-            (final: prev: rec {
-              jre = prev.jdk$java_version$_headless;
-              jdk = jre;
-            })
+            (self: super:
+              let jvm = super.jdk$java_version$_headless;
+              in {
+                jre = jvm;
+                jdk = jvm;
+              })
           ];
         };
-      in { devShell = import ./shell.nix { inherit pkgs; }; });
+      in { devShell = with pkgs;
+          mkShell {
+            buildInputs = [ jre ammonite coursier bloop sbt scalafmt ];
+          };
+      });
 }
diff --git a/src/main/g8/shell.nix b/src/main/g8/shell.nix
index a599aac..fa2a56c 100644
--- a/src/main/g8/shell.nix
+++ b/src/main/g8/shell.nix
@@ -1,11 +1,6 @@
-{ pkgs ? import <nixpkgs> {
-  overlays = [
-    (final: prev: rec {
-      jre = prev.jdk$java_version$_headless;
-      jdk = jre;
-    })
-  ];
-} }:
-
-with pkgs;
-mkShell { buildInputs = [ jre ammonite coursier bloop sbt scalafmt ]; }
+(import (let lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+in fetchTarball {
+  url =
+    "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+  sha256 = lock.nodes.flake-compat.locked.narHash;
+}) { src = ./.; }).shellNix