diff --git a/flake.nix b/flake.nix
index 658aa30..f96957b 100644
--- a/flake.nix
+++ b/flake.nix
@@ -14,8 +14,9 @@
     pvv-calendar-bot.url = "git+https://git.pvv.ntnu.no/Projects/calendar-bot.git";
     pvv-calendar-bot.inputs.nixpkgs.follows = "nixpkgs";
 
-    # Last release compatible with 23.05
     matrix-next.url = "github:dali99/nixos-matrix-modules";
+    # https://github.com/NixOS/nixpkgs/pull/273262
+    nixpkgs-matrix-buildenv.url = "github:dali99/nixpkgs/synapse-buildenv";
 
     grzegorz.url = "github:Programvareverkstedet/grzegorz";
     grzegorz.inputs.nixpkgs.follows = "nixpkgs-unstable";
diff --git a/hosts/bicep/services/matrix/synapse.nix b/hosts/bicep/services/matrix/synapse.nix
index 2b0d160..27e7ad5 100644
--- a/hosts/bicep/services/matrix/synapse.nix
+++ b/hosts/bicep/services/matrix/synapse.nix
@@ -29,6 +29,7 @@ in {
 
   services.matrix-synapse-next = {
     enable = true;
+    package = inputs.nixpkgs-matrix-buildenv.legacyPackages.x86_64-linux.matrix-synapse;
 
     plugins = [
       (pkgs.python3Packages.callPackage ./smtp-authenticator { })