diff --git a/modules/nixos.nix b/modules/nixos.nix
index 211618b..e1d34b7 100644
--- a/modules/nixos.nix
+++ b/modules/nixos.nix
@@ -46,8 +46,8 @@ in
       environment = {
         SSH_CD_SOCKET_ADDRESS = "${cfg.host}:${toString cfg.port}";
         SSH_CD_CERT_DIR = cfg.dataDir;
-        SSH_CD_VALIDATE_EXPIRY = true;
-        SSH_CD_VALIDATE_SERIAL = false;
+        SSH_CD_VALIDATE_EXPIRY = "true";
+        SSH_CD_VALIDATE_SERIAL = "false";
         SSH_CD_CA = cfg.ca;
         RUST_LOG = "debug";
       };