diff --git a/processor/logic/GameBoard.cpp b/processor/logic/GameBoard.cpp
index ad2c7f2..514e130 100644
--- a/processor/logic/GameBoard.cpp
+++ b/processor/logic/GameBoard.cpp
@@ -80,7 +80,8 @@ void GameBoard::turnUpdate() {
 				tile.unit += 1;
 
 			if (tile.type == TileType::Swamp) {
-				tile.unit -= 1;
+				if (tile.unit > 0) 
+					tile.unit -= 1;
 				if (tile.unit == 0)
 					tile.owner = neutral_player;
 			}