diff --git a/src/core/game/Game.ts b/src/core/game/Game.ts
index 56834b3d6..14837f109 100644
--- a/src/core/game/Game.ts
+++ b/src/core/game/Game.ts
@@ -562,7 +562,7 @@ export interface Player {
   unitsOwned(type: UnitType): number;
   buildableUnits(
     tile: TileRef | null,
-    TransportShipFilter?: TransportShipFilter,
+    transportShipFilter?: TransportShipFilter,
   ): BuildableUnit[];
   canBuild(type: UnitType, targetTile: TileRef): TileRef | false;
   buildUnit<T extends UnitType>(