diff --git a/nixos/modules/monitoring/server/grafana.nix b/nixos/modules/monitoring/server/grafana.nix
index 9ff69194cde31c5ef82966dfb2e28ed01a757fe1..2526f4f5e9fadc03670dd3cd440d2f2ed5287495 100644
--- a/nixos/modules/monitoring/server/grafana.nix
+++ b/nixos/modules/monitoring/server/grafana.nix
@@ -119,7 +119,7 @@ in {
           # Grafana considers it "sign up" to let in a user it has
           # never seen before.
           allow_sign_up = true;
-          client_secret_file = cfg.googleOAuthClientSecretFile;
+          client_secret = "$__file{${toString cfg.googleOAuthClientSecretFile}}";
           client_id = cfg.googleOAuthClientID;
         };