diff --git a/include/boost/core/bit.hpp b/include/boost/core/bit.hpp
index f4305b9..7efb7c7 100644
--- a/include/boost/core/bit.hpp
+++ b/include/boost/core/bit.hpp
@@ -446,10 +446,13 @@ BOOST_CONSTEXPR bool has_single_bit( T x ) BOOST_NOEXCEPT
     return x != 0 && ( x & ( x - 1 ) ) == 0;
 }
 
+// bit_width should return int, https://cplusplus.github.io/LWG/issue3656
+
 template<class T>
 BOOST_CONSTEXPR T bit_width( T x ) BOOST_NOEXCEPT
 {
-    return std::numeric_limits<T>::digits - boost::core::countl_zero( x );
+    return static_cast<T>(
+        std::numeric_limits<T>::digits - boost::core::countl_zero( x ) );
 }
 
 template<class T>