diff --git a/src/terrain_translation.cpp b/src/terrain_translation.cpp
index cfe38edfe83..0378d754345 100644
--- a/src/terrain_translation.cpp
+++ b/src/terrain_translation.cpp
@@ -299,7 +299,7 @@ t_map read_game_map(const std::string& str,	std::map<int, coordinate>& starting_
 				starting_positions[starting_position].y = y;
 			} else {
 				// add new position
-				struct coordinate coord = {x, y};
+				const struct coordinate coord = {x, y};
 				starting_positions.insert(std::pair<int, coordinate>(starting_position, coord));
 			}
 		}