diff --git a/src/parser3.h b/src/parser3.h
index 311d2bb..e9bfac6 100644
--- a/src/parser3.h
+++ b/src/parser3.h
@@ -1134,7 +1134,7 @@ inline PRESERVE_NONE WeaselJsonStatus n_string2(Parser3 *self, char *buf,
     }
     MUSTTAIL return Parser3::keepGoing(self, buf, bufEnd);
   default:
-    __builtin_unreachable();
+    [[unlikely]] return WeaselJson_REJECT;
   }
 }