diff --git a/libcxx/include/__tree b/libcxx/include/__tree
index 6ca1a623536f2..74b20d5b6f814 100644
--- a/libcxx/include/__tree
+++ b/libcxx/include/__tree
@@ -1388,8 +1388,9 @@ __tree<_Tp, _Compare, _Allocator>& __tree<_Tp, _Compare, _Allocator>::operator=(
     if (__root())
       __root()->__parent_ = __end_node();
   }
-  __begin_node_ = static_cast<__end_node_pointer>(std::__tree_min(static_cast<__node_base_pointer>(__end_node())));
-  __size_       = __t.size();
+  __begin_node_ =
+      __end_node()->__left_ ? static_cast<__end_node_pointer>(std::__tree_min(__end_node()->__left_)) : __end_node();
+  __size_ = __t.size();
 
   return *this;
 }