diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -2658,7 +2658,7 @@
     if (__sz == __cap)
     {
         __grow_by(__cap, 1, __sz, __sz, 0);
-        __is_short = !__is_long();
+        __is_short = false;
     }
     pointer __p;
     if (__is_short)