diff --git a/include/boost/intrusive/detail/tree_algorithms.hpp b/include/boost/intrusive/detail/tree_algorithms.hpp
index 1dc6b51..9ad2b4e 100644
--- a/include/boost/intrusive/detail/tree_algorithms.hpp
+++ b/include/boost/intrusive/detail/tree_algorithms.hpp
@@ -1501,7 +1501,7 @@ class tree_algorithms
 
    static node_ptr vine_to_subtree(node_ptr old_root, std::size_t count)
    {
-      std::size_t leaf_nodes = count + 1 - ((size_t) 1 << floor_log2 (count + 1));
+      std::size_t leaf_nodes = count + 1 - ((std::size_t) 1 << floor_log2 (count + 1));
       std::size_t vine_nodes = count - leaf_nodes;
 
       node_ptr new_root = compress_subtree(old_root, leaf_nodes);