diff --git a/include/boost/intrusive/detail/math.hpp b/include/boost/intrusive/detail/math.hpp
index 4901053..200f8b8 100644
--- a/include/boost/intrusive/detail/math.hpp
+++ b/include/boost/intrusive/detail/math.hpp
@@ -262,7 +262,7 @@ template<class SizeType, class Enabler = void >
 struct sqrt2_pow_max;
 
 template <class SizeType>
-struct sqrt2_pow_max<SizeType, typename enable_if< numbits_eq<SizeType, 32> >::type>
+struct sqrt2_pow_max<SizeType, typename voider<typename enable_if< numbits_eq<SizeType, 32> >::type>::type>
 {
    static const SizeType value = 0xb504f334;
    static const std::size_t pow   = 31;
@@ -271,7 +271,7 @@ struct sqrt2_pow_max<SizeType, typename enable_if< numbits_eq<SizeType, 32> >::t
 #ifndef BOOST_NO_INT64_T
 
 template <class SizeType>
-struct sqrt2_pow_max<SizeType, typename enable_if< numbits_eq<SizeType, 64> >::type>
+struct sqrt2_pow_max<SizeType, typename voider<typename enable_if< numbits_eq<SizeType, 64> >::type>::type>
 {
    static const SizeType value = 0xb504f333f9de6484ull;
    static const std::size_t pow   = 63;