Index: include/__hash_table
===================================================================
--- include/__hash_table
+++ include/__hash_table
@@ -136,7 +136,7 @@
 size_t
 __next_hash_pow2(size_t __n)
 {
-    return size_t(1) << (std::numeric_limits<size_t>::digits - __clz(__n-1));
+    return (__n > 1) ? (size_t(1) << (std::numeric_limits<size_t>::digits - __clz(__n-1))) : __n;
 }