diff --git a/nixos/modules/services/matrix/matrix-authentication-service.nix b/nixos/modules/services/matrix/matrix-authentication-service.nix
index 18648d2e3451..4b57643e4090 100644
--- a/nixos/modules/services/matrix/matrix-authentication-service.nix
+++ b/nixos/modules/services/matrix/matrix-authentication-service.nix
@@ -45,9 +45,7 @@ let
       pruned;
   configFile = format.generate "config.yaml" finalSettings;
 
-  extraConfigFiles = lib.imap0 (
-    i: _: "$CREDENTIALS_DIRECTORY/config-${toString i}"
-  ) cfg.extraConfigFiles;
+  extraConfigFiles = lib.imap0 (i: _: "%d/config-${toString i}") cfg.extraConfigFiles;
   runtimeConfig = "/run/matrix-authentication-service/config.yaml";
 in
 {