Index: source/graphics/MapIO.cpp
===================================================================
--- source/graphics/MapIO.cpp
+++ source/graphics/MapIO.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2018 Wildfire Games.
+/* Copyright (C) 2019 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -86,8 +86,9 @@
 			int offset = std::min(y, tileSize - 1) * mapLineSkip + std::min(x, tileSize - 1) * bytesPP;
 
 			// Pick color channel with highest value
-			u16 value = std::max({mapdata[offset], mapdata[offset + bytesPP], mapdata[offset + bytesPP * 2]});
-			value = mapdata[offset];
+			u16 value = static_cast<u16>(std::max({mapdata[offset], 
+			                                       mapdata[offset + bytesPP], 
+			                                       mapdata[offset + bytesPP * 2]}));
 
 			heightmap[(tileSize - y) * (tileSize + 1) + x] = clamp(value * 256, 0, 65535);
 		}