diff --git a/lib/mapping/CMap.cpp b/lib/mapping/CMap.cpp
index f4ad85b46..824dca05e 100644
--- a/lib/mapping/CMap.cpp
+++ b/lib/mapping/CMap.cpp
@@ -334,7 +334,11 @@ bool CMap::isCoastalTile(const int3 & pos) const
 
 bool CMap::isInTheMap(const int3 & pos) const
 {
-	return pos.x >= 0 && pos.y >= 0 && pos.z >= 0 && pos.x < width && pos.y < height && pos.z <= (twoLevel ? 1 : 0);
+	// Check whether coord < 0 is done implicitly. Negative signed int overflows to unsigned number larger than all signed ints.
+	return
+		static_cast<uint32_t>(pos.x) < static_cast<uint32_t>(width) &&
+		static_cast<uint32_t>(pos.y) < static_cast<uint32_t>(height) &&
+		static_cast<uint32_t>(pos.z) <= (twoLevel ? 1 : 0);
 }
 
 TerrainTile & CMap::getTile(const int3 & tile)