diff --git a/module.nix b/module.nix
index 66cc318..73e384e 100644
--- a/module.nix
+++ b/module.nix
@@ -84,9 +84,9 @@ in
         authenticate = true;
       };
       extraConfig = {
-        "SMTP_ENABLE_STARTTLS_AUTO" = false;
-        "SMTP_TLS" = false;
-        "SMTP_SSL" = false;
+        "SMTP_ENABLE_STARTTLS_AUTO" = "false";
+        "SMTP_TLS" = "false";
+        "SMTP_SSL" = "false";
       };
     };