diff --git a/nixos/tests/prometheus-exporters.nix b/nixos/tests/prometheus-exporters.nix
index e27de66a16a0..4bad56991cc6 100644
--- a/nixos/tests/prometheus-exporters.nix
+++ b/nixos/tests/prometheus-exporters.nix
@@ -969,7 +969,7 @@ let
     pgbouncer = {
       exporterConfig = {
         enable = true;
-        connectionString = "postgres://admin:@localhost:6432/pgbouncer?sslmode=disable";
+        connectionStringFile = pkgs.writeText "connection.conf" "postgres://admin:@localhost:6432/pgbouncer?sslmode=disable";
       };
 
       metricProvider = {