diff --git a/checks/matrix-synapse/default.nix b/checks/matrix-synapse/default.nix
index 0e879e3d..10395d26 100644
--- a/checks/matrix-synapse/default.nix
+++ b/checks/matrix-synapse/default.nix
@@ -4,7 +4,12 @@
     name = "matrix-synapse";
 
     nodes.machine =
-      { self, lib, ... }:
+      {
+        config,
+        self,
+        lib,
+        ...
+      }:
       {
         imports = [
           self.clanModules.matrix-synapse
@@ -12,17 +17,48 @@
           {
             clanCore.machineName = "machine";
             clanCore.clanDir = ./.;
-            clan.matrix-synapse = {
-              domain = "clan.test";
-            };
-          }
-          {
-            # secret override
-            clanCore.facts.services.matrix-synapse.secret.synapse-registration_shared_secret.path = "${./synapse-registration_shared_secret}";
+
             services.nginx.virtualHosts."matrix.clan.test" = {
               enableACME = lib.mkForce false;
               forceSSL = lib.mkForce false;
             };
+            clan.matrix-synapse.domain = "clan.test";
+            clan.matrix-synapse.users.admin.admin = true;
+            clan.matrix-synapse.users.someuser = { };
+
+            clanCore.facts.secretStore = "vm";
+
+            # because we use systemd-tmpfiles to copy the secrets, we need to a seperate systemd-tmpfiles call to provison them.
+            boot.postBootCommands = "${config.systemd.package}/bin/systemd-tmpfiles --create /etc/tmpfiles.d/00-vmsecrets.conf";
+
+            systemd.tmpfiles.settings."00-vmsecrets" = {
+              # run before 00-nixos.conf
+              "/etc/secrets" = {
+                d.mode = "0700";
+                z.mode = "0700";
+              };
+              "/etc/secrets/synapse-registration_shared_secret" = {
+                f.argument = "registration_shared_secret: supersecret";
+                z = {
+                  mode = "0400";
+                  user = "root";
+                };
+              };
+              "/etc/secrets/matrix-password-admin" = {
+                f.argument = "matrix-password1";
+                z = {
+                  mode = "0400";
+                  user = "root";
+                };
+              };
+              "/etc/secrets/matrix-password-someuser" = {
+                f.argument = "matrix-password2";
+                z = {
+                  mode = "0400";
+                  user = "root";
+                };
+              };
+            };
           }
         ];
       };
@@ -31,6 +67,12 @@
       machine.wait_for_unit("matrix-synapse")
       machine.succeed("${pkgs.netcat}/bin/nc -z -v ::1 8008")
       machine.succeed("${pkgs.curl}/bin/curl -Ssf -L http://localhost/_matrix/static/ -H 'Host: matrix.clan.test'")
+
+      machine.systemctl("restart matrix-synapse >&2") # check if user creation is idempotent
+      machine.execute("journalctl -u matrix-synapse --no-pager >&2")
+      machine.wait_for_unit("matrix-synapse")
+      machine.succeed("${pkgs.netcat}/bin/nc -z -v ::1 8008")
+      machine.succeed("${pkgs.curl}/bin/curl -Ssf -L http://localhost/_matrix/static/ -H 'Host: matrix.clan.test'")
     '';
   }
 )
diff --git a/clanModules/matrix-synapse/0001-register_new_matrix_user-add-password-file-flag.patch b/clanModules/matrix-synapse/0001-register_new_matrix_user-add-password-file-flag.patch
new file mode 100644
index 00000000..39e9ea2c
--- /dev/null
+++ b/clanModules/matrix-synapse/0001-register_new_matrix_user-add-password-file-flag.patch
@@ -0,0 +1,84 @@
+From df45634a92944dcab4edb02fb5e478911c58fdd6 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
+Date: Tue, 11 Jun 2024 11:40:47 +0200
+Subject: [PATCH] register_new_matrix_user: add password-file flag
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+getpass in python exist on stdin to be a tty, hence we cannot just pipe
+into register_new_matrix_user. --password-file instead works better and
+it would also allow the use of stdin if /dev/stdin is passed.
+
+Signed-off-by: Jörg Thalheim <joerg@thalheim.io>
+---
+ debian/register_new_matrix_user.ronn         |  6 +++++-
+ synapse/_scripts/register_new_matrix_user.py | 16 ++++++++++++++--
+ 2 files changed, 19 insertions(+), 3 deletions(-)
+
+diff --git a/debian/register_new_matrix_user.ronn b/debian/register_new_matrix_user.ronn
+index 0410b1f4c..e39bef448 100644
+--- a/debian/register_new_matrix_user.ronn
++++ b/debian/register_new_matrix_user.ronn
+@@ -32,7 +32,11 @@ A sample YAML file accepted by `register_new_matrix_user` is described below:
+ 
+   * `-p`, `--password`:
+     New password for user. Will prompt if omitted. Supplying the password
+-    on the command line is not recommended. Use the STDIN instead.
++    on the command line is not recommended. Use password-file if possible.
++
++  * `--password-file`:
++    File containing the new password for user. Will prompt if omitted.
++    This is a more secure alternative to specifying the password on the command line.
+ 
+   * `-a`, `--admin`:
+     Register new user as an admin. Will prompt if omitted.
+diff --git a/synapse/_scripts/register_new_matrix_user.py b/synapse/_scripts/register_new_matrix_user.py
+index 77a7129ee..f067e6832 100644
+--- a/synapse/_scripts/register_new_matrix_user.py
++++ b/synapse/_scripts/register_new_matrix_user.py
+@@ -173,12 +173,18 @@ def main() -> None:
+         default=None,
+         help="Local part of the new user. Will prompt if omitted.",
+     )
+-    parser.add_argument(
++    password_group = parser.add_mutually_exclusive_group()
++    password_group.add_argument(
+         "-p",
+         "--password",
+         default=None,
+         help="New password for user. Will prompt if omitted.",
+     )
++    password_group.add_argument(
++        "--password-file",
++        default=None,
++        help="File containing the new password for user. Will prompt if omitted.",
++    )
+     parser.add_argument(
+         "-t",
+         "--user_type",
+@@ -247,6 +253,12 @@ def main() -> None:
+             print(_NO_SHARED_SECRET_OPTS_ERROR, file=sys.stderr)
+             sys.exit(1)
+ 
++    password = ""
++    if args.password_file:
++        password = _read_file(args.password_file, "password-file").strip()
++    else:
++        password = args.password
++
+     if args.server_url:
+         server_url = args.server_url
+     elif config is not None:
+@@ -270,7 +282,7 @@ def main() -> None:
+         admin = args.admin
+ 
+     register_new_user(
+-        args.user, args.password, server_url, secret, admin, args.user_type
++        args.user, password, server_url, secret, admin, args.user_type
+     )
+ 
+ 
+-- 
+2.44.1
+
diff --git a/clanModules/matrix-synapse/default.nix b/clanModules/matrix-synapse/default.nix
index 6a06708d..3c94d2e0 100644
--- a/clanModules/matrix-synapse/default.nix
+++ b/clanModules/matrix-synapse/default.nix
@@ -16,16 +16,58 @@ let
           > $out/config.json < ${pkgs.element-web}/config.json
         ln -s $out/config.json $out/config.${nginx-vhost}.json
       '';
+
+  # FIXME: This was taken from upstream. Drop this when our patch is upstream
+  synapseCfg = config.services.matrix-synapse;
+  wantedExtras =
+    synapseCfg.extras
+    ++ lib.optional (synapseCfg.settings ? oidc_providers) "oidc"
+    ++ lib.optional (synapseCfg.settings ? jwt_config) "jwt"
+    ++ lib.optional (synapseCfg.settings ? saml2_config) "saml2"
+    ++ lib.optional (synapseCfg.settings ? redis) "redis"
+    ++ lib.optional (synapseCfg.settings ? sentry) "sentry"
+    ++ lib.optional (synapseCfg.settings ? user_directory) "user-search"
+    ++ lib.optional (synapseCfg.settings.url_preview_enabled) "url-preview"
+    ++ lib.optional (synapseCfg.settings.database.name == "psycopg2") "postgres";
+
 in
 {
+  options.services.matrix-synapse.package = lib.mkOption { readOnly = false; };
   options.clan.matrix-synapse = {
     domain = lib.mkOption {
       type = lib.types.str;
       description = "The domain name of the matrix server";
       example = "example.com";
     };
+    users = lib.mkOption {
+      type = lib.types.attrsOf (
+        lib.types.submodule (
+          { name, ... }:
+          {
+            options = {
+              name = lib.mkOption {
+                type = lib.types.str;
+                default = name;
+                description = "The name of the user";
+              };
+
+              admin = lib.mkOption {
+                type = lib.types.bool;
+                default = false;
+                description = "Whether the user should be an admin";
+              };
+            };
+          }
+        )
+      );
+      description = "A list of users. Not that only new users will be created and existing ones are not modified.";
+      example.alice = {
+        admin = true;
+      };
+    };
   };
   imports = [
+    ../postgresql
     (lib.mkRemovedOptionModule [
       "clan"
       "matrix-synapse"
@@ -36,6 +78,18 @@ in
   ];
   config = {
     services.matrix-synapse = {
+      package = lib.mkForce (
+        pkgs.matrix-synapse.override {
+          matrix-synapse-unwrapped = pkgs.matrix-synapse.unwrapped.overrideAttrs (_old: {
+            doInstallCheck = false; # too slow, nixpkgs maintainer already run this.
+            # see: https://github.com/element-hq/synapse/pull/17294
+            patches = [ ./0001-register_new_matrix_user-add-password-file-flag.patch ];
+          });
+          extras = wantedExtras;
+          plugins = synapseCfg.plugins;
+        }
+      );
+
       enable = true;
       settings = {
         server_name = cfg.domain;
@@ -70,7 +124,10 @@ in
       };
       extraConfigFiles = [ "/run/synapse-registration-shared-secret.yaml" ];
     };
-    systemd.tmpfiles.settings."synapse" = {
+
+    security.wrappers = lib.mkForce { }; # unsupported in unprivileged containers
+
+    systemd.tmpfiles.settings."01-matrix" = {
       "/run/synapse-registration-shared-secret.yaml" = {
         C.argument =
           config.clanCore.facts.services.matrix-synapse.secret.synapse-registration_shared_secret.path;
@@ -90,16 +147,64 @@ in
       OWNER = "matrix-synapse";
     };
 
-    clanCore.facts.services."matrix-synapse" = {
-      secret."synapse-registration_shared_secret" = { };
-      generator.path = with pkgs; [
-        coreutils
-        pwgen
-      ];
-      generator.script = ''
-        echo "registration_shared_secret: $(pwgen -s 32 1)" > "$secrets"/synapse-registration_shared_secret
-      '';
-    };
+    clanCore.facts.services =
+      {
+        "matrix-synapse" = {
+          secret."synapse-registration_shared_secret" = { };
+          generator.path = with pkgs; [
+            coreutils
+            pwgen
+          ];
+          generator.script = ''
+            echo "registration_shared_secret: $(pwgen -s 32 1)" > "$secrets"/synapse-registration_shared_secret
+          '';
+        };
+      }
+      // lib.mapAttrs' (
+        name: user:
+        lib.nameValuePair "matrix-password-${user.name}" {
+          secret."matrix-password-${user.name}" = { };
+          generator.path = with pkgs; [
+            coreutils
+            pwgen
+          ];
+          generator.script = ''
+            xkcdpass -n 4 -d - > "$secrets"/${lib.escapeShellArg "matrix-password-${user.name}"}
+          '';
+        }
+      ) cfg.users;
+
+    systemd.services.matrix-synapse =
+      let
+        usersScript =
+          ''
+            while ! ${pkgs.netcat}/bin/nc -z -v ::1 8008; do
+              if ! kill -0 "$MAINPID"; then exit 1; fi
+              sleep 1;
+            done
+
+            headers=$(mktemp)
+            trap 'rm -f "$headers"' EXIT
+
+            cat > "$headers" <<EOF
+            Authorization: Bearer $(cat /run/synapse-registration-shared-secret.yaml| sed -n 's/registration_shared_secret: //p')
+            EOF
+          ''
+          + lib.concatMapStringsSep "\n" (user: ''
+            # only create user if it doesn't exist
+            if ! curl --header "$headers" "http://localhost:8008/_synapse/admin/v1/whois/${user.name}@${cfg.domain}" >&2; then
+              /run/current-system/sw/bin/matrix-synapse-register_new_matrix_user --password-file ${
+                config.clanCore.facts.services."matrix-password-${user.name}".secret."matrix-password-${user.name}".path
+              } --user "${user.name}" ${if user.admin then "--admin" else "--no-admin"}
+            fi
+          '') (lib.attrValues cfg.users);
+      in
+      {
+        path = [ pkgs.curl ];
+        serviceConfig.ExecStartPost = [
+          (''+${pkgs.writeShellScript "matrix-synapse-create-users" usersScript}'')
+        ];
+      };
 
     services.nginx = {
       enable = true;