diff --git a/Guide/package-management.markdown b/Guide/package-management.markdown
index 3d781b355..0c29b701e 100644
--- a/Guide/package-management.markdown
+++ b/Guide/package-management.markdown
@@ -371,47 +371,53 @@ After that try to run `devenv up`.
 
 ### Building Postgres With Extensions
 
-**TODO: Fix this for IHP v1.1.0**
-
 For some applications you may want to install custom postgres extension
 libraries and have them available in the nix store.
 
 For example to enable the [postgis](https://postgis.net/) spatial
 and geographic objects in PostgreSQL add
-`postgresExtensions = (p: [ p.postgis ]);` to your project's `default.nix` file as
-an attribute of the `"{ihp}/NixSupport/default.nix"` expression.
+`services.postgres.extensions = extensions: [ extensions.postgis ];` to your project's `flake.nix`:
 
 
 ```nix
-let
-    ihp = builtins.fetchGit {
-        url = "https://github.com/digitallyinduced/ihp.git";
-        rev = "c6d40612697bb7905802f23b7753702d33b9e2c1";
-    };
-    haskellEnv = import "${ihp}/NixSupport/default.nix" {
-        ihp = ihp;
-        postgresExtensions = (p: [ p.postgis ]);
-        haskellDeps = p: with p; [
-            cabal-install
-            base
-            wai
-            text
-            hlint
-            p.ihp
-            google-oauth2
-        ];
-        otherDeps = p: with p; [
-        ];
-        projectPath = ./.;
+{
+    inputs = {
+        ihp.url = "path:///Users/marc/digitallyinduced/ihp";
+        ihp.inputs.nixpkgs.url = "github:mpscholten/nixpkgs/fix-th-desugar";
+        nixpkgs.follows = "ihp/nixpkgs";
+        flake-parts.follows = "ihp/flake-parts";
+        devenv.follows = "ihp/devenv";
+        systems.follows = "ihp/systems";
     };
-in
-    haskellEnv
+
+    outputs = inputs@{ ihp, flake-parts, systems, nixpkgs, ... }:
+        flake-parts.lib.mkFlake { inherit inputs; } {
+            systems = import systems;
+            imports = [ ihp.flakeModules.default ];
+
+            perSystem = { pkgs, ... }: {
+                ihp = {
+                    inherit appName;
+                    enable = true;
+                    projectPath = ./.;
+                    packages = with pkgs; [];
+                    haskellPackages = p: with p; [
+                        # ...
+                    ];
+                };
+                devenv.shells.default = {
+                    services.postgres.extensions = extensions: [ extensions.postgis ];
+                };
+            };
+        };
+}
+
 ```
 
 Behind the scenes this will pass a function to the postgres nix expressions `postgresql.withPackages`
 function making the extension in your app's nix store postgres package.
 
-After the install you can run `create extension postgis;` to enable all the features of the
+After the install you can run `CREATE EXTENSION postgis;` to enable all the features of the
 installed extension.
 
 ### Stopping Nix From Running Tests for a Haskell Dependency
diff --git a/NixSupport/default.nix b/NixSupport/default.nix
index 0b44c4fd4..b754aeaea 100644
--- a/NixSupport/default.nix
+++ b/NixSupport/default.nix
@@ -7,9 +7,7 @@
 , otherDeps ? (p: [])
 , projectPath ? ./.
 , withHoogle ? false
-, postgresExtensions ? (p: [])
 , optimized ? false
-, includeDevTools ? !optimized # Include Postgres?
 , rtsFlags ? ""
 , appName ? "app"
 , optimizationLevel ? "2"
@@ -175,7 +173,6 @@ in
             [ pkgs.makeWrapper
             pkgs.cacert # Needed for npm install to work from within the IHP build process
             ]
-            (if includeDevTools then [(pkgs.postgresql_13.withPackages postgresExtensions)] else [])
         ];
         shellHook = "eval $(egrep ^export ${allHaskellPackages}/bin/ghc)";
         enableParallelBuilding = true;
diff --git a/flake-module.nix b/flake-module.nix
index 9748e195d..a9e54de7d 100644
--- a/flake-module.nix
+++ b/flake-module.nix
@@ -139,8 +139,6 @@ ihpFlake:
                     haskellDeps = cfg.haskellPackages;
                     otherDeps = p: cfg.packages;
                     projectPath = cfg.projectPath;
-                    # Dev tools are not needed in the release build
-                    includeDevTools = false;
                     # Set optimized = true to get more optimized binaries, but slower build times
                     optimized = true;
                     ghc = ghcCompiler;
@@ -156,7 +154,6 @@ ihpFlake:
                     haskellDeps = cfg.haskellPackages;
                     otherDeps = p: cfg.packages;
                     projectPath = cfg.projectPath;
-                    includeDevTools = false;
                     optimized = false;
                     ghc = ghcCompiler;
                     pkgs = pkgs;
@@ -204,9 +201,21 @@ ihpFlake:
             };
 
             devenv.shells.default = lib.mkIf cfg.enable {
-                packages = [ ghcCompiler.ihp ghcCompiler.ihp-ide pkgs.postgresql_13 pkgs.gnumake ]
+                packages = [ ghcCompiler.ihp ghcCompiler.ihp-ide pkgs.gnumake ]
                     ++ cfg.packages
                     ++ [pkgs.mktemp] # Without this 'make build/bin/RunUnoptimizedProdServer' fails on macOS
+                    ++ [(let cfg = config.devenv.shells.default.services.postgres; in
+                        if cfg.extensions != null
+                        then
+                          if builtins.hasAttr "withPackages" cfg.package
+                          then cfg.package.withPackages cfg.extensions
+                          else
+                            builtins.throw ''
+                              Cannot add extensions to the PostgreSQL package.
+                              `services.postgres.package` is missing the `withPackages` attribute. Did you already add extensions to the package?
+                            ''
+                        else cfg.package
+                    )]
                     ;
 
                 /*
@@ -239,6 +248,7 @@ ihpFlake:
                 # As the devenv postgres uses a different location for the socket
                 # this would break lots of known commands such as `make db`
                 services.postgres.enable = false;
+                services.postgres.package = pkgs.postgresql_13;
                 services.postgres.initialDatabases = [
                     {
                     name = "app";