diff --git a/nixos/modules/services/continuous-integration/hydra/default.nix b/nixos/modules/services/continuous-integration/hydra/default.nix
index d3945f2370d7..b7ba37a37b73 100644
--- a/nixos/modules/services/continuous-integration/hydra/default.nix
+++ b/nixos/modules/services/continuous-integration/hydra/default.nix
@@ -320,7 +320,7 @@ in
           ${optionalString haveLocalDB ''
             if ! [ -e ${baseDir}/.db-created ]; then
               runuser -u ${config.services.postgresql.superUser} ${config.services.postgresql.package}/bin/createuser hydra
-              runuser -u ${config.services.postgresql.superUser} ${config.services.postgresql.package}/bin/createdb -O hydra hydra
+              runuser -u ${config.services.postgresql.superUser} ${config.services.postgresql.package}/bin/createdb -- -O hydra hydra
               touch ${baseDir}/.db-created
             fi
             echo "create extension if not exists pg_trgm" | runuser -u ${config.services.postgresql.superUser} -- ${config.services.postgresql.package}/bin/psql hydra