diff -r -u boost_1_63_0-1/boost/gil/channel_algorithm.hpp boost_1_63_0-2/boost/gil/channel_algorithm.hpp
--- boost_1_63_0-1/boost/gil/channel_algorithm.hpp	2016-12-22 13:33:15.000000000 +0100
+++ boost_1_63_0-2/boost/gil/channel_algorithm.hpp	2017-04-04 15:30:29.314315624 +0200
@@ -51,7 +51,7 @@
 
 
 template <typename UnsignedIntegralChannel>
-struct unsigned_integral_max_value : public mpl::integral_c<UnsignedIntegralChannel,-1> {};
+struct unsigned_integral_max_value : public mpl::integral_c<UnsignedIntegralChannel,static_cast<UnsignedIntegralChannel>(-1)> {};
 
 template <>
 struct unsigned_integral_max_value<uint8_t> : public mpl::integral_c<uint32_t,0xFF> {};