diff --git a/.gitignore b/.gitignore
index 799db665..f8bf5718 100644
--- a/.gitignore
+++ b/.gitignore
@@ -38,6 +38,7 @@ t/jobs/declarative/project.json
 hydra-config.h
 hydra-config.h.in
 result
+result-*
 outputs
 config
 stamp-h1
diff --git a/Makefile.am b/Makefile.am
index 9e06ebdb..a28e3f33 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -5,8 +5,8 @@ endif
 
 BOOTCLEAN_SUBDIRS = $(SUBDIRS)
 DIST_SUBDIRS      = $(SUBDIRS)
-EXTRA_DIST        = hydra-module.nix
+EXTRA_DIST        = nixos-modules/hydra.nix
 
-install-data-local: hydra-module.nix
+install-data-local: nixos-modules/hydra.nix
 	$(INSTALL) -d $(DESTDIR)$(datadir)/nix
-	$(INSTALL_DATA) hydra-module.nix $(DESTDIR)$(datadir)/nix/
+	$(INSTALL_DATA) nixos-modules/hydra.nix $(DESTDIR)$(datadir)/nix/hydra-module.nix
diff --git a/flake.nix b/flake.nix
index 71fd6c6d..30aa61c0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -15,9 +15,11 @@
       systems = [ "x86_64-linux" "aarch64-linux" ];
       forEachSystem = nixpkgs.lib.genAttrs systems;
 
+      overlayList = [ self.overlays.default nix.overlays.default ];
+
       pkgsBySystem = forEachSystem (system: import nixpkgs {
         inherit system;
-        overlays = [ self.overlays.default nix.overlays.default ];
+        overlays = overlayList;
       });
 
       # NixOS configuration used for VM tests.
@@ -386,50 +388,8 @@
         default = pkgsBySystem.${system}.hydra;
       });
 
-      nixosModules.hydra = {
-        imports = [ ./hydra-module.nix ];
-        nixpkgs.overlays = [ self.overlays.default nix.overlays.default ];
-      };
-
-      nixosModules.hydraTest = { pkgs, ... }: {
-        imports = [ self.nixosModules.hydra ];
-
-        services.hydra-dev.enable = true;
-        services.hydra-dev.hydraURL = "http://hydra.example.org";
-        services.hydra-dev.notificationSender = "admin@hydra.example.org";
-
-        systemd.services.hydra-send-stats.enable = false;
-
-        services.postgresql.enable = true;
-        services.postgresql.package = pkgs.postgresql_11;
-
-        # The following is to work around the following error from hydra-server:
-        #   [error] Caught exception in engine "Cannot determine local time zone"
-        time.timeZone = "UTC";
-
-        nix.extraOptions = ''
-          allowed-uris = https://github.com/
-        '';
-      };
-
-      nixosModules.hydraProxy = {
-        services.httpd = {
-          enable = true;
-          adminAddr = "hydra-admin@example.org";
-          extraConfig = ''
-            <Proxy *>
-              Order deny,allow
-              Allow from all
-            </Proxy>
-
-            ProxyRequests     Off
-            ProxyPreserveHost On
-            ProxyPass         /apache-errors !
-            ErrorDocument 503 /apache-errors/503.html
-            ProxyPass         /       http://127.0.0.1:3000/ retry=5 disablereuse=on
-            ProxyPassReverse  /       http://127.0.0.1:3000/
-          '';
-        };
+      nixosModules = import ./nixos-modules {
+        overlays = overlayList;
       };
 
       nixosConfigurations.container = nixpkgs.lib.nixosSystem {
diff --git a/nixos-modules/default.nix b/nixos-modules/default.nix
new file mode 100644
index 00000000..6fc19d31
--- /dev/null
+++ b/nixos-modules/default.nix
@@ -0,0 +1,49 @@
+{ overlays }:
+
+rec {
+  hydra = {
+    imports = [ ./hydra.nix ];
+    nixpkgs = { inherit overlays; };
+  };
+
+  hydraTest = { pkgs, ... }: {
+    imports = [ hydra ];
+
+    services.hydra-dev.enable = true;
+    services.hydra-dev.hydraURL = "http://hydra.example.org";
+    services.hydra-dev.notificationSender = "admin@hydra.example.org";
+
+    systemd.services.hydra-send-stats.enable = false;
+
+    services.postgresql.enable = true;
+    services.postgresql.package = pkgs.postgresql_11;
+
+    # The following is to work around the following error from hydra-server:
+    #   [error] Caught exception in engine "Cannot determine local time zone"
+    time.timeZone = "UTC";
+
+    nix.extraOptions = ''
+      allowed-uris = https://github.com/
+    '';
+  };
+
+  hydraProxy = {
+    services.httpd = {
+      enable = true;
+      adminAddr = "hydra-admin@example.org";
+      extraConfig = ''
+        <Proxy *>
+          Order deny,allow
+          Allow from all
+        </Proxy>
+
+        ProxyRequests     Off
+        ProxyPreserveHost On
+        ProxyPass         /apache-errors !
+        ErrorDocument 503 /apache-errors/503.html
+        ProxyPass         /       http://127.0.0.1:3000/ retry=5 disablereuse=on
+        ProxyPassReverse  /       http://127.0.0.1:3000/
+      '';
+    };
+  };
+}
diff --git a/hydra-module.nix b/nixos-modules/hydra.nix
similarity index 100%
rename from hydra-module.nix
rename to nixos-modules/hydra.nix
diff --git a/package.nix b/package.nix
index 73ef9b3f..d5e6bb69 100644
--- a/package.nix
+++ b/package.nix
@@ -143,7 +143,7 @@ stdenv.mkDerivation (finalAttrs: {
       ./Makefile.am
       ./src
       ./doc
-      ./hydra-module.nix
+      ./nixos-modules/hydra.nix
       # These are always needed to appease Automake
       ./t/Makefile.am
       ./t/jobs/config.nix.in