diff --git a/nixos/modules/services/matrix/synapse.nix b/nixos/modules/services/matrix/synapse.nix
index b6b51b21c796..2a4104a4ec2b 100644
--- a/nixos/modules/services/matrix/synapse.nix
+++ b/nixos/modules/services/matrix/synapse.nix
@@ -755,8 +755,8 @@ in {
         Group = "matrix-synapse";
         WorkingDirectory = cfg.dataDir;
         ExecStartPre = [ ("+" + (pkgs.writeShellScript "matrix-synapse-fix-permissions" ''
-          chown matrix-synapse:matrix-synapse ${cfg.dataDir}/homeserver.signing.key
-          chmod 0600 ${cfg.dataDir}/homeserver.signing.key
+          chown matrix-synapse:matrix-synapse ${cfg.settings.signing_key_path}
+          chmod 0600 ${cfg.settings.signing_key_path}
         '')) ];
         ExecStart = ''
           ${cfg.package}/bin/synapse_homeserver \