diff --git a/include/boost/intrusive/sgtree.hpp b/include/boost/intrusive/sgtree.hpp
index 2b7cb60..cd4d8bc 100644
--- a/include/boost/intrusive/sgtree.hpp
+++ b/include/boost/intrusive/sgtree.hpp
@@ -133,7 +133,8 @@ struct alpha_holder
    typedef boost::intrusive::detail::h_alpha_t           h_alpha_t;
    typedef boost::intrusive::detail::alpha_by_max_size_t multiply_by_alpha_t;
 
-   alpha_holder() : max_tree_size_(0)
+   alpha_holder()
+      : max_tree_size_()
    {  set_alpha(0.70711f);   } // ~1/sqrt(2)
 
    float get_alpha() const
@@ -166,6 +167,10 @@ struct alpha_holder<false, SizeType>
    typedef boost::intrusive::detail::h_alpha_sqrt2_t           h_alpha_t;
    typedef boost::intrusive::detail::alpha_0_75_by_max_size_t  multiply_by_alpha_t;
 
+   alpha_holder()
+      : max_tree_size_()
+   {}
+
    float get_alpha() const
    {  return 0.70710677f;  }