diff --git a/lib/serializer.mjs b/lib/serializer.mjs
index 57bbdb1..7a147c8 100644
--- a/lib/serializer.mjs
+++ b/lib/serializer.mjs
@@ -69,9 +69,6 @@ function serialize_operator({name, args}, state) {
         case "maybe": {
             return `${serialized_args[0]}?`;
         }
-        case "maybe": {
-            return `${serialized_args[0]}?`;
-        }
         case "never": {
             return null;
         }